The United Nations secretary general, António Guterres, has urged Donald Trump not to scrap the Iran nuclear deal, saying that the Middle East would become an even more dangerous place if such an important diplomatic victory was thrown away with nothing better to replace it.

The US president is due to decide next week whether to withdraw from the agreement – by which Iran accepted nuclear inspections in return for a loosening of economic sanctions – despite intense political opposition from Tehran and the key European powers Britain, Germany and France.

“If one day there is a better agreement to replace it it’s fine, but we should not scrap it unless we have a good alternative,” Guterres said in an interview with BBC Radio 4.

“I believe the JCPOA [the Iran nuclear deal] was an important diplomatic victory and I think it will be important to preserve it but I also believe there are areas in which it will be very important to have a meaningful dialogue because I see the region in a very dangerous position,” he said.

Guterres also said the risks of a confrontation between Israel and Iran “were there”, adding “we need to do everything to avoid those risks”.

The secretary general is in London for a three-day visit, where he is consulting on what measures can be taken to prevent paralysis at the UN security council due primarily to a breakdown in relations between Russia and the west.

Referring to American concerns about Iran’s wider behaviour, he said: “I understand the concerns of some countries in relation to the Iranian influence in other countries of the region. So I think we should separate things.”

The UK, France and Germany are planning to keep campaigning to preserve the deal next week, and may even make common cause with Tehran to preserve the deal if Trump pulls out and allows US sanctions on Iran to be reimposed.

In a bid to satisfy Trump’s concerns, the three countries have already agreed to seek a supplementary deal with Iran that would cover Iran’s general behaviour in the region, Iran’s use of ballistic missiles and the future of the deal once it expires, the so-called sunset clause.

The former UK foreign secretary Jack Straw also intervened to urge Washington not to scrap the deal telling the Guardian: “The great irony of President Trump’s position that it will do the opposite of what it intends. It will undermine President Hassan Rouhani and all those trying to reform Iran. It will also end all the restraints on a serious nuclear programme”.

He added “I hope the European nations will actively cooperate to support regulations as they did in 1996 to protect their economies and firms from the impact of any American sanctions if they are imposed.”

In 1996 the US Congress passed an Iran and Libya Sanctions Act that imposed sanctions on all firms, including non-American firms, if they were doing business with either country. The European Union later that year passed a blocking statute to make it illegal for any European firm to abide by US sanctions imposed due to the law by Congress. It also took the US to World Trade Organisation arguing it was in breach of free trade regulations by trying to impose restrictions on non-US firms.

So far the EU has not discussed in public whether it has a plan B to try to preserve the deal with Iran in the event of Trump pulling out, preferring instead to focus on the last-ditch efforts to persuade Trump to rethink.

Diplomats are divided over whether Trump will regard himself as on a roll after the shift towards peace in North Korea, and whether that will make him more or less willing to listen to his European partners.

Tags: ; ; ;