Reports earlier this week that as many as 150 people drowned in the Mediterranean were wrong, aid organisations said on Friday.

A 16-year-old boy from The Gambia was found clinging to a fuel can in the sea on Wednesday, and he told rescuers about 147 others on his vessel had died when it sank.

Probably still in shock after he was taken to the Italian island of Lampedusa, the boy told humanitarian workers he was the only survivor of the wreck, Cecile Pouilly, a spokeswoman for the UNHCR, told reporters.

Nearly 150 migrants feared dead after boat sinks

When 140 others disembarked at a different port on Thursday, several identified the boy as having been on the same boat.

"So we have pretty good information that this tragedy didn't occur as was initially reported," said Joel Millman, spokesman for the International Organization for Migration.

"We try to be as conservative as possible and only report what we know. This was not one of those cases."

Some 650 asylum seekers are estimated to have died trying to reach Europe by crossing the Mediterranean so far this year, and arrivals in Italy are up about 30 percent from the same period last year.

Last year 4,600 people died at sea.