Nearly 6,000 migrants who crossed the Mediterranean have reached Italy since Tuesday, the International Organization for Migration said today.
Experts warned the surge in arrivals is set to continue because of better weather and warming seas.
That crackdown may have triggered a switch to the more dangerous route from North Africa to Italy .
In the week to 13 April, arrivals in Italy were 173% higher than the previous week, while arrivals in Greece were 76% lower.
The migrants landing in Italy told officials they all crossed from Libya, with most travelling on rubber dinghies.
However, the IOM said there was no evidence yet the Turkey-EU deal was linked to the latest surge.
Those reaching the EU via Greece were usually from Syria and Iraq, while the recent arrivals in Italy were mainly citizens of African countries.
Federico Soda, the head of the IOM’s office in Rome, said: “Many of them were from sub-Saharan Africa, and we have noticed an increase in numbers from the Horn of Africa, particularly Eritreans.
“There have been very few Syrians leaving from Libya in recent months.”
So far this year, the IOM has recorded more than 23,000 arrivals in Italy and more than 153,000 in Greece.
David Cameron and German Chancellor Angela Merkel held talks aimed at tackling the crisis today.
No 10 later said there were fears the route from Libya would become more popular as the weather continued to improve.
The EU’s Operation Sophia has been targeting smuggling gangs using the passage to exploit vulnerable refugees and economic migrants.
During their 25-minute phone call, Mr Cameron and Mrs Merkel discussed “what more could be done to make sure that is as robust as possible as we move into a season where we are concerns we could see the numbers increase on that route”, Downing Street said.
The Prime Minister is desperate to avoid a repeat of last summer’s nightly TV pictures of migrant boats landing on Europe’ shores, as the countdown to June’s crunch EU referendum continues.
“In” supporters fear the images could persuade undecided voters to back Brexit .