Fifty-eight other people, including five children, were found alive during the rescue in the early hours of Wednesday and transported to Lampedusa by the coastguard, according to spokesman Roberto D’Arrigo.

Lampedusa mayor Filippo Mannino said seven people, including two children, were being treated in hospital for “hypothermia and intoxication from hydrocarbon fumes”.

The coastguard rescue was staged some 135 kilometres (85 miles) off the Italian island inside Libyan search-and-rescue waters.

The boat was spotted by an Italian reconnaissance plane on Tuesday but there were no Libyan coastguard or civilian ships in the area to assist, D’Arrigo said.

A decision was taken to send an Italian coastguard vessel from Lampedusa.

D’Arrigo said some of the migrants may have died while being transported back to Lampedusa in particularly rough weather conditions with waves up to seven metres (23 feet) high.

Lampedusa is a key landing point for migrants crossing the Mediterranean Sea from North Africa, with many dying trying the dangerous journey.

So far this year, 624 migrants have died or gone missing in the central Mediterranean, according to the UN’s International Organization for Migration.

Lampedusa’s last migrant disaster occurred in August last year, when 27 people died in two shipwrecks off the coast.

According to the interior ministry, 6,117 migrants have landed on Italy’s shores so far this year.