ROME (Reuters) - More than 2,000 migrants were rescued from boats in the Mediterranean on Friday, Italy’s coastguard said, as numbers soared for the third year running in the build up to summer.

Migrants sit in their boat during a rescue operation by Italian navy ship Grecale (unseen) off the coast of Sicily, Italy, in this handout picture courtesy of the Italian Marina Militare released on May 6 2016. Marina Militare/Handout via REUTERS

Around 14,000 people were taken off often flimsy vessels over the whole week, the United Nations and the coastguard said, and hundreds may have drowned, survivors and boat crews added, though there are no official estimates of casualties.

Italian Navy ship Vega plucked about 130 people off a “half-submerged” large rubber boat - one of 17 operations coordinated by the coastguard on Friday. There were no details on how many were on board before it deflated.

The Vega recovered 10 bodies, Ansa news agency said. The coastguard and the navy said they could not confirm the number.

The coastguard said the warmer weather and calmer seas had led to a surge in the number of people trying to cross from Libya, where people smugglers operate with relative impunity. Numbers managing to reach Italy were comparable to the same period last year and the year before.

The migrants, many of whom do not know how to swim and do not have life jackets, pay hundreds or thousands of dollars to make the crossing.

They are piled onto flimsy rubber boats or old fishing vessels, and as dramatic images from the crew of the Italian Navy ship Bettica showed on Wednesday, they can be tossed into the water in a matter of seconds.

The images show the moment a blue fishing boat capsized, sending hundreds of migrants tumbling into the sea. About 240 women and children had already been rescued, but an unknown number were trapped in the hull. Only five bodies were recovered and 562 were saved.

Testimony from survivors suggests there were still many people below deck who were not able to escape, according to the U.N. refugee agency, while the Bettica captain estimated that “some 100” may have been lost.

On Thursday, when 4,000 were rescued in 22 separate operations, survivors from another overturned fishing boat say some 200 may have drowned, a sharp rise from the 20-30 originally estimated, according to an Italian Interior Ministry source. Some 15 bodies were recovered, he said.

“It’s obvious that no matter the great effort made by rescuers, when the numbers are as high as we’re seeing this week, it’s very risky,” said Federico Fossi, a spokesman for the United Nations High Commissioner for Refugees (UNHCR) in Rome.

“But in terms of numbers it’s the third year that this is ‘normal’,” Fossi said. “It’s the beginning of the high season and we’re still at slightly fewer arrivals as the same period last year.”

In 2014 and 2015, more than 320,000 boat migrants arrived on Italian shores, and an estimated 7,000 died in the Mediterranean as they sought to reach Europe, according to the International Organization for Migration.

On Friday the IOM said it estimates total Mediterranean deaths at sea to be 1,475 this year.