Here’s a summary of what we know:
Brussels remains on lockdown on Saturday night, with the metro system, shopping centres and public buildings closed. The city’s mayor has ordered all restaurants and cafes to close tonight.
The government raised the terror alert level to level four – “very serious” – for the Brussels region. “Analysis shows a serious and imminent threat that requires taking specific security measures as well as specific recommendations for the public,” an official statement said.
The heightened terror threat is thought to have been sparked by fears that Salah Abdeslam is in hiding in the Brussels area. The 26-year-old French man is believed to be one of the ringleaders of the Paris attacks in which 130 people died last Friday. He has reportedly been in touch with friends on Skype asking for help in getting back to Syria.
Turkish police arrested three terror suspects, including a Belgian of Moroccan origin who is suspected of action as a scout for the cell that launched the Paris attacks.
Labour leader Jeremy Corbyn said that Britain must not be “drawn into responses that feed a cycle of violence and hate” following the Paris attacks.
The United Nations Security Council voted to approve a French-backed resolution calling on all member states to do everything possible to eradicate the threat posed by Islamic State jihadis.
David Cameron will visit Paris on Monday to meet with French president François Hollande.
The US European Command has issued a 72-hour travel restriction on travel to Brussels by all US military personnel as well as civilian Pentagon employees, contractors and command-sponsored family members and dependents. The command said on its website that “for those already in Brussels, everyone is to shelter in place and remain at home”.
Brussels is home to the headquarters of the US-led NATO alliance. NATO’s military headquarters, officially known as Supreme Headquarters Allied Powers Europe, is about 70km (45 miles) south of the city.
A Belgian man of Moroccan origin has been arrested in Turkey on suspicion that he scouted the target sites for attacks that killed 130 people in Paris a week ago, a Turkish government official said. The official, confirming a report by the Dogan news agency, said two other men were also arrested.
The Belgian, Ahmet Dahmani, was arrested at a luxury hotel in the southern coastal city of Antalya. The 26-year-old had been staying in the resort since Monday, according to the report.
Special forces have arrested four people at Place du Grand Sablon in Brussels, according to a report from RTL. The four were in a suspicious vehicle. No further details as yet.
Police are now saying that the three men arrested on Blackfriars Road are suspected care thieves. Quite why they needed to deploy helicopters and armed units, and cordon off the whole area, is still not clear.
The Scotland Yard statement says:
At 13:44hrs on Saturday, 21 November, officers stopped a vehicle on BlackfriarsRoad at the junction with St George’s Circus. The occupants of the vehicle – three men – were arrested on suspicion of theft of a motor vehicle.
They currently remain in custody at a south London police station. Roads have now reopened.
It looks like the scare on Southwark is over, with the Met police saying they don’t believe that the incident is terror-related, according to a tweet from a Channel 4 News editor.
Scotland Yard has sent a terse statement about apparently still ongoing incident on Blackfriars Road. It says:
At 13:44hrs on Saturday, 21 November, officers stopped a vehicle on Blackfriars Road at the junction with Cambridge Circus.
The occupants of the vehicle – three men – were arrested.
Local road closures are in place.
More tweets are being posted about the unfolding situation in south London, where armed police have cordoned off Blackfriars Road, close to Southwark tube station.
“Ongoing incident” at #blackfriars – police have closed multiple roads
— Charlie Cuff (@CharlieBCuff) 21 ноября 2015
— Cal Rimmer (@cally__x) 21 ноября 2015
There seems to be a security alert much closer to home. A tweet warns that armed police are out near Southwark station, just south of the River Thames in London.
Salah Abdeslam may be equipped with a suicide belt, according to Hamza Attou, one of two suspects charged this week by Belgian authorities for allegedly helping Abdeslam return to the country after the Paris terror attacks.
Carine Couquelet, Attou’s lawyer, told Belgian TV channel LCI that her client had said that Abdeslam seemed very agitated in the vehicle that brought him back to Brussels from Paris.
“My client was very scared, they did not talk much and he [Abdeslam] did not mention the presence of weapons, but he wore a kind of big jacket, possibly a suicide belt,” she was quoted as saying by L’Echo.
Belgium’s interior ministry has published an infographic with information on the measures they are asking people to take in light of the heightened threat of a terrorist attack in Brussels.
The Belgian government is asking anyone with information on the whereabouts of Salah Abdeslam to call an official hotline and is also asking people to be aware of suspicious packages or behaviour.
Abdeslam, a Brussels resident, whose brother Brahim blew himself up at a Paris bar, is believed to be in Belgium and is the subject of a huge manhunt. Both grew up in the poor Molenbeek district of Brussels, where a cache of weapons was found yesterday, before going to join the Islamic State group in Syria.
A suspect arrested in Belgium on Thursday has been charged with terrorist offences in connection with the Paris attacks. His identity has not been revealed.
Here are some pictures of central Brussels, where heavily armed police and soldiers are still patrolling the streets after the terror alert was raised to its highest level.
The Belgian prime minister, Charles Michel, has told a press conference that the decision to raise the terror alert in Brussels was taken “based on quite precise information about the risk of an attack like the one that happened in Paris.”
Paris police have extended a ban on demonstrations and other gatherings in the region, shutting down plans for a major protest at next week’s UN climate conference.
The French capital’s police department issued a statement on Saturday saying the ban is being extended to 30 November because of “the current context,” including a nationwide state of emergency that’s been extended for three months, AP reports.
The department notes extra security concerns around the arrival of more than 100 heads of state for the U.N. climate conference that starts in a week. The march by environmental groups was scheduled for 29 November, but has been cancelled.
Police are requiring all major concert venues to install special security measures.
L’Echo has more details on the search which uncovered a cache of weapons in Molenbeek last night.
A search was conducted on Friday at the home of a suspect placed under arrest, federal prosecutors said on Saturday. Some weapons have been discovered, but no explosives or explosive belt.
The suspect was arrested Thursday in the series of searches carried out in Brussels. The person concerned is suspected of involvement in terrorist attacks and participation in activities of a terrorist group.
All shopping centres in Brussels are being closed this afternoon, according to reports.
At least one, the Woluwe shopping centre in the east of Brussels, was in the past few minutes also being evacuated, according to local media reports and Twitter users.
The reasons for the sudden decision, which was not part of the heightened security measures announced earlier today, are still unclear.
A tweet from Brussels shows armoured personnel carriers in the streets of the city, which is home to many European institutions as well as the headquarters of NATO.
An eyewitness says the city looks like a military base.
— M. Cruickshank CN (@MJ_Cruickshank) November 21, 2015
Belgian police discovered a cache of weapons and explosives on Friday night when they raided a property in the Vandepeerboom Street area of Molenbeek, Brussels, according to a report in La Capitale.
The Belgian paper reports that a large arsenal of weapons and ammunition was discovered, as well as explosives. At this stage it is not known whether the raid led to any arrests.
The discovery of the arsenal could be the reason for the heightened terror alert in the Belgian capital today.
Security has been stepped up at key water supply sites in Paris, after the French prime minister warned the country could not rule out attacks from “chemical or biological weapons”.
The heightened security comes as reports claim that biohazard suits have been stolen from a Paris hospital, the Telegraph reports.
Eau de Paris, the municipal water company, yesterday told Le Parisien that access to its sites has been limited to only the necessary service personnel, and that they have been accredited by the defence ministry.
The measures have been in place since last Saturday.
A terrorist arsenal was discovered during overnight searches in a suburb of Brussels, Belgian paper Dernière Heure reports.
Chemicals and explosives were among the items found in the Molenbeek suburb, a rundown neighbourhood where Paris attacker Abdelhamid Abaaoud grew up.