Rome  - The bodies of 20 would-be immigrants, along with 23 survivors, were recovered in the sea off Libya, but 200 more were feared missing after the boat that was carrying them capsized, officials said Tuesday.

The accident probably took place on Sunday and involved a boat carrying 257 people, according to Laurence Hart, the International Organization for Migration's chief of mission in Tripoli.

"The Libyan authorities say they have terminated the rescue operation," making it unlikely more survivors would be found, Hart told German Press Agency dpa.

At least 10 Egyptian nationals were among the dead, Egypt's Assistant Foreign Minister for Consular Affairs, Ahmed Rizq, told Egypt's official MENA news agency.

The vessel, which was heading for Italy from Libya, is believed to have overturned some 30 nautical miles off the Libyan coast.

Initial reports from Libya suggested at least two vessels were involved in the accident, raising fears that some 500 people may be missing.

However, Italian coastguard officials later said they believed Libyan authorities were referring to a rescue operation on Sunday, in which an Italian freighter picked up some 356 would-be immigrants stranded on a vessel at sea and then carried them to the Libyan port of Tripoli.

Of these, some 66 were from Bangladesh, while the others appeared to be from West Africa, including Nigeria and Horn of Africa nations including Eritrea and Somalia, Hart told dpa.

He also said Libyan authorities on Tuesday reported losing radio contact with two fishing vessels that may have been used to carry would-be immigrants. The whereabouts of the two vessels remain unknown. "It is a terrible tragedy which happened outside the waters of our responsibility," Italy's Interior Minister Robert Maroni said, referring to the dead and missing would-be immigrants.

Maroni said he had "no reason not to believe" that Libyan authorities had done everything possible to save the those involved in the accident.

On Monday more than 400 would-be immigrants who are also believed to have sailed from Libya, landed in Sicily.

Maroni said such arrivals from North Africa would stop once a Rome-Tripoli agreement involving the use of Libyan naval patrols to monitor the North African country's coastline comes into effect in May.

But the office of the United Nations High Commissioner for Refugees (UNHCR) in Geneva warned that a surge of immigrant arrivals could be expected over the coming months as weather conditions improve over the northern summer

"This is the beginning of the smuggling season in the Mediterranean," UNHCR spokesman Ron Redmond said, noting that the latest incident highlighted the dangers facing so-called irregular migrants.

The UN's High Commissioner for Refugees, Antonio Guterres, was quoted as saying that this is the "latest tragic example of a global phenomenon in which desperate people take desperate measures to escape conflict, persecution and poverty in search of a better life."

The mixed movement of economic migrants and asylum seekers was making distinguishing between them more difficult.

Redmond said the rescued people had been taken to detention centers in Libya and that UNHCR had been asked to give humanitarian assistance to those in need and screen for refugees.

Libya, with a relatively well-off economy based on oil and natural gas reserves, has become a destination for migrants from other parts of Africa, particularly from the western coast.

The International Organization for Migration estimated some 1 million to 1.5 million undocumented migrants work in Libya in the informal sector.

According to Italian government figures, a total of 36,900 would- be immigrants arrived in Italy by sea in 2008, a 75-per-cent increase over the previous year. Of these some 31,000 landed on Lampedusa, an islet situated south of Sicily. (dpa)