More than 700 migrants were feared dead following three shipwrecks off the Libyan coast in the past week. The deaths come amid a surge in the number of asylum seekers making the treacherous Mediterranean crossing as the warmer weather brings calmer seas.

The likely death toll was confirmed by Carlotta Sami, a UN refugee agency spokeswoman, after one of the busiest weeks on record for the Italian Navy and Coast Guard, which rescued about 15,000 people during operations south of Italy’s shores.

The vast majority of new migrant arrivals, and those who drowned, are sub-Saharan Africans who transited through Libya.

There is no evidence of a massive movement of Syrian and other Middle Eastern refugees trying to cross to Italy from Libya after the closure of Balkan route and the EU’s controversial deal with Turkey, which effectively brought sea crossings to Greece to a halt.

The high number of deaths off Libya this week confirms the dangers involved in crossing the central Mediterranean to Europe, a longer and riskier journey than the path across the Aegean Sea favoured by most migrants last year.

On Wednesday, about 100 migrants went missing, five were confirmed dead, and more than 500 people were saved after their rickety boat capsized.

On Thursday, 91 migrants were rescued after their boat took on water and sank. Survivors reported that another 400 people had been on board and were missing.

On Friday, 160 more people were feared missing, and 45 confirmed dead, after another vessel sank off the Libyan coast, bringing the death toll for the combined three days to 700. Among them, about 40 children are estimated to have died.

The grim figure is unlikely to trigger any major policy shift in Europe. After a single shipwreck off Libya killed more than 700 people in April 2015, the EU boosted funding for search and rescue operations in the central Mediterranean which have largely been Italy’s burden. But the EU has since struggled to forge common policies on overhauling the asylum system and redistributing migrants across member states, amid resistance from many countries to welcoming refugees.

The most recent deaths are likely to provoke more calls from aid agencies to boost so-called “humanitarian corridors” that would allow asylum seekers to be directly transported to Europe after being processed in third countries.

But the number of migrants involved in such programmes have been very small and scaling them up would be fraught with logistical and political obstacles.

“Sunday counting victims. Macabre exercise. Will the world realise the 700 people would have deserved safe passage?” the UN’s Ms Sami said on Twitter.

Italy is likely to reiterate its call for the EU to ramp up efforts to reach deals with African countries that would force them to stop migrants from leaving and accept them back once deported in exchange for financial assistance — along the lines of the agreement with Turkey.

However, striking such agreements with a plethora of African countries is much more diplomatically difficult than it was with a single government in the case of Turkey.

Libya, the main transit country for migrants travelling to Italy, is consumed by political chaos as a government of national unity tries to establish itself amid the rise of Isis in the country and a lingering civil war between different militias.

Meanwhile, Italian authorities are trying to disperse the newly rescued migrants across the country as quickly as possible, bringing them to different ports across Sicily, as well as Calabria, Puglia and Sardinia.

So far, the number of migrants arriving in Italy this year — about 46,000 — remains roughly in line with the number which arrived in 2015, easing fears of a massive increase in 2016.

However, Save the Children, the aid agency, has estimated that many more minors have been crossing this year compared with 2015.

If the pace of the past week were to continue, the final tally of migrants for the year is likely to exceed last year’s total of 153,000 and could even beat the 2014 record of 170,000 arrivals.

As the migration crisis flared up again south of Italy, Pope Francis, who has been one of the most vocal supporters for the rights of refugees, held a meeting at the Vatican over the weekend in which he showed a group of children a life jacket used by a drowned girl who was brought to him by a rescue worker.

“He said: ‘Father, I failed. There was a girl, in the waves, but I could not save her. All that is left is her life jacket’,” Pope Francis said.

“I don’t want to upset you, but you are brave and you know the truth … Many children … they are in danger,” the Argentine pontiff said.