More than 200 illegal migrants were missing presumed dead as 21 bodies were recovered after a violent storm off Libya's Mediterranean coast, the International Organisation for Migration said Tuesday.
"A boat with 257 migrants on board sank on Sunday off the coast of Libya. Twenty-three people were saved and 21 bodies were retrieved," Laurence Hart, the IOM chief of mission in Tripoli, told AFP.
An earlier IOM toll out of the organisation's Geneva headquarters put the number of missing at 300.
Hart said the Libyan coastguards were also searching for two other boats, but that "we don't yet know if these are fishing boats or had migrants on board."
In Geneva, the UN High Commissioner for Refugees (UNHCR) said Egyptians, Tunisians and Africans were on boats that that were wrecked some 30 kilometres (20 miles) off Libya.
"We are shocked by the reports of hundreds of people trying to reach Europe missing off the coast of Libya," UNHCR spokesman Ron Redmond said in a statement.
"Details are still sketchy, but reports indicate a number of vessels carrying several hundred people set sail from the coast of Libya in the direction of Italy over the last few days.
"At least one boat reportedly went down and hundreds of people aboard are reported missing."
Twenty-three people "of African and Arab nationality" were saved by Libyan coastguards, Tuesday's edition of the private Libyan newspaper Oea said.
First reports of the disaster emerged late on Monday out of Egypt, with state news agency MENA quoting foreign ministry official Ahmed Rizq as saying a ship carrying more than 250 illegal migrants had gone down off Libya.
He told MENA that 20 people, including six Egyptians, were saved by Libyan rescue workers, and that the boat had set sail from Sidi Bilal, near Tripoli, on Sunday morning.
"This is the beginning of the smuggling season in the Mediterranean," Redmond said on Tuesday.
"This tragic incident illustrates, once again, the dangers faced by people caught in mixed irregular movements of migrants and refugees in the Mediterranean and elsewhere which every year cost thousands of lives."
With 1,770 kilometres (1,106 miles) of coastline, Libya has become a popular destination country and transit point for immigrants from eastern and southern Africa headed for Europe.
On Monday, a Libyan interior ministry source said an Italian tanker rescued 350 illegal migrants after their vessel ran into trouble.
A ship carrying illegal migrants bound for Europe also sank off Libya on Sunday, with 21 people drowning and an unknown number of people missing, the source added.
The UNHCR quoted High Commissioner Antonio Guterres as calling Sunday's sinking "the latest tragic example of a global phenomenon in which desperate people take desperate measures to escape conflict, persecution and poverty."
Italy and Libya are to launch joint sea patrols aimed at stopping the illegal traffic.
Italian Interior Minister Roberto Maroni said in Rome on Monday the patrols would begin on May 15, a day he expects to "mark the end" of illegal migration from North Africa.
"Last year 36,000 people arrived in Italy by sea from North Africa. Some 75 percent of them applied for asylum and about 50 percent of those received some form of international protection from the Italian authorities," the UNHCR said.
The Council of Europe secretary general, Terry Davis, said from Strasbourg that he was "deeply distressed about this death trap at the borders of Europe."
He called for governments, despite the global economic crisis, to "continue to create economic opportunities in the countries of origin of these migrants and thus allow people to provide for their families without risking their lives on a perilous journey to Europe."