Italy’s Coast Guard rescued 57 migrants from two boats that capsized during the night in rough seas south of a tiny Italian island and recovered two bodies, authorities said.

In a statement, the coast guard says it recovered the body of a boy and a woman from one of the capsized vessels and quotes survivors as saying some 30 migrants were missing.

Some 20 others were stranded on rocks after a third shipwreck on Sunday.

According to those who were rescued, 28 people were missing from one vessel and three from the other.

The rescued migrants were found 23 nautical miles (42.5 kilometres) south-west of Lampedusa.

Meanwhile, several migrants were clinging desperately to jagged rocks of a tall reef off Lampedusa since early Saturday after a third boat crashed into the craggy outcropping west of the island’s lighthouse.

Strong winds and powerful waves made any Coast Guard rescue too dangerous.

The coast guard office in Palermo requested the help of a Sicily-based Alpine and Cave Rescue group, which flew two experts aboard an Italian air force helicopter.

The experts were planning to rescue the stranded migrants using the helicopter, the mountaineering group said.

In all, 34 migrants had been stranded for two nights on the reef, including a woman who is eight months pregnant, said newspaper Giornale di Sicilia. She was taken to a hospital, it said.

Earlier, helicopters dropped food and water down to the migrants, Italian state TV reported.

Ignazio Schintu, an official of the Italian Red Cross says so many migrants have made the crossing in smugglers’ unseaworthy boats launched from Libya and Tunisia in recent days that 2,450 migrants were currently housed at Lampedusa’s temporary residence, which has a capacity of about 400.

Once the winds slacken and the seas turn calm, Italy will resume ferrying hundreds of migrants to Sicily to ease the overcrowding, Mr Schintu told state TV.

The two boats that capsized in open seas were believed to have set out from Sfax — a Tunisian port — on Thursday, when sea conditions were good, according to authorities.

But since conditions were forecast to turn bad on Saturday, “it’s even more criminal for smugglers to let them leave,” said Flavio Di Giacomo, a spokesperson from the UN migration agency IOM.

Before Saturday, a total of 1,814 migrants were known to have perished while attempting the Mediterranean crossing to Italy in boats launched from Tunisia or Libya, he said.

Libyan departures used to be riskier, he said, but because Tunisia-based smugglers have been using particularly flimsy vessels lately, that route is becoming increasingly deadlier.

Migrants from sub-Saharan Africa are setting out from Tunisia in “fragile iron vessels that after 24 hours, often break in two, and the migrants fall into the sea,” Mr Di Giacomo said.