Everything happened so quickly. The boat overturned in less than five minutes

Survivor Moulay Badgi

Divers are also scouring the wreck of the Joola, which overturned after leaving Ziguinchor in the south of Senegal on Thursday night with almost 800 people on board.

Eighty-eight people have been confirmed dead by the authorities and 60 are known to have survived.

Relatives have crowded the quayside and hospitals in Dakar, hoping for news of those on board but there is increasing pessimism that more survivors will be found.

The prime minister has blamed heavy rains and winds for the disaster, but questions have been raised about the overloading of the ferry way beyond its capacity, and the boat's state of repair.

'It was terrible'

Details of how and why the Joola tipped over are still sketchy, but survivors have said it all happened in a matter of minutes.

"Everything happened so quickly. The boat overturned in less than five minutes," said Moulay Badgi.

"I heard the crying of the children and it was terrible".

"We managed to swim out of the water, yelling for help," said survivor Moussa Ndong, speaking to the Associated Press by telephone from a hospital in Gambia.

Survivors stayed on top of the capsized boat for two hours, until fishing boats arrived to pluck them off.

"It was horrible, because we were hearing people screaming from underneath," he said.

"The boat went down so fast. It was so unbelievable".

Security officials at the port in Dakar had to put up barriers to hold back the hundreds of anguished relatives who have gathered there, waiting for news.

Lists have now been posted of those known to have survived.

Safety questions

The government has promised a full inquiry into what caused the disaster - which a former minister said was the first of its kind in Senegal's history.

Attention has focused on the overcrowding of the ferry, which has a capacity of 550 but had 796 on board.

Questions have also been raised about maintenance, as the Joola had only recently resumed service after undergoing repairs.

Local press reports have suggested that one of the boat's motors may not have been working.

The BBC's Chris Simpson in Dakar says Senegal is one of the more open democracies in West Africa, with a challenging press and boisterous opposition, and full coherent explanations will be demanded.

The government has declared three days of national mourning.

Travelling by boat is a popular method of transport between Dakar and Ziguinchor because a civil war has made the route by road treacherous.