The European Union acknowledged Tuesday efforts to deal with illegal migrants crossing the Mediterranean were not working after reports that shipwrecked Africans were left clinging to a tuna net for days while boats would not take them on board.

"Cooperation isn't yet working," said EU spokesman Friso Roscam Abbing. "It's quite a difficult situation."

Roscam Abbing was addressing media reports that 27 migrants held on for three days to a tuna pen towed by a Maltese trawler after their boat sank before they were eventually rescued by an Italian vessel.

Roscam Abbing said the EU would investigate the incident and other recent reports where stricken migrants were either not picked up by passing European boats or refused entry to ports after they had been rescued by overcrowded vessels.

He told reporters EU authorities were "first going to analyze the situation to see why coordination didn't work well, as it manifestly didn't."

He recalled that skippers had an obligation to rescue those in danger at sea.

"No captain of any vessel can avoid the obligation to save people's lives, that is quite clear for the countries concerned," Roscam Abbing said. "That's a very clear moral obligation, and that's also a legal obligation."

In a front page story headlined "Europe's Shame" the British daily The Independent on Saturday said the skipper of the Maltese boat refused to take the migrants on board through fear of becoming entangled in a diplomatic wrangle that would endanger his cargo of tuna. The report also said Libya failed to respond to calls to help the migrants.