A boat packed with hundreds of refugees trying to flee Libya sank just off the coast near Tripoli late last week, the United Nations’ refugee agency and the International Organization for Migration said Monday.

The ship, which left from the Tripoli area, capsized just hundreds of yards from the shore, the organizations said, citing accounts by refugees who arrived on the Italian island of Lampedusa on Sunday on a vessel that left immediately after the one that capsized. But precise details, including the number of people who died, remained unclear.

Refugees said they saw bodies floating in the water as they sailed through the area, said Laura Boldrini, a spokeswoman for the Office of the U.N. High Commissioner for Refugees.

“They said they saw the boat capsizing in front of them,” Boldrini said. It was not clear how many bodies had been recovered. The Libyan government has severely restricted the movements of reporters in Tripoli, hampering their ability to collect information.

Thousands of people have fled Libya since fighting started in February between rebels and forces loyal to Moammar Gaddafi, who has led the country since 1969. Lampedusa, which is about 180 miles off the coast of Libya, has been flooded with refugees. Aid agencies have said that the refugees have made the sea journey in dangerous circumstances.

Some have come over in small craft. More recently, Boldrini said, larger ships have been making the voyage, and they are often overloaded. She said that the ship that arrived immediately before the one that sank was carrying 655 people and that the one that followed was carrying 798 people.

A spokesman for the International Organization for Migration, which has also been involved in aid work in Lampedusa, said one survivor of the shipwreck told them that she made it back to the Libyan shore but was forced onto the next ship by armed men. It was unclear who the men were. Libyan officials did not respond to requests for comment.

“Some of the people who survived this shipwreck were obviously not keen to get on another boat,” said Jean-Philippe Chauzy, a spokesman for the International Organization for Migration. “They and others waiting in the area were forced onto the ship by armed men, who were apparently shooting into the air.”

Chauzy said that refugees had told his organization that they had to pay little or no money for the passage to Lampedusa but that the people running the boats took all their possessions before allowing them on the ship.

Tripoli’s Roman Catholic bishop, Giovanni Martinelli, who has close ties to Eritrean Catholic migrants working in Libya, told the Italian daily Corriere della Sera that Eritreans and Somalis were among those on board the ship that sank.

Ships in poor condition have made fleeing Libya extremely dangerous. The Guardian, a British newspaper, reported Monday that 61 people died after their boat ran out of fuel and was left to drift in the Mediterranean for 16 days at the end of March. The newspaper reported that the migrants made contact with a NATO aircraft carrier and a military helicopter, but that they were not rescued. NATO said it had not received any distress calls.

And a ship carrying refugees ran aground near Lampedusa over the weekend. All aboard were rescued.

Meanwhile, heavy fighting continued in the rebel-held city of Misurata on Monday, according to residents there reached via Skype. The city is under siege by government forces and has come under heavy assault in recent weeks.

The city’s main fuel depot, which was hit early Saturday, is still ablaze, said Mohammed Abdullah, a professor. “It is still burning — the oil is still burning,” the Misurata resident said. Rebel officials said this weekend that the city has enough supplies to last three or four weeks.

A ship chartered by the International Committee of the Red Cross arrived in Misurata Monday morning, bringing medical supplies for the hospital, spare parts to repair water and electrical supply systems, and baby food for the civilian population, according a Red Cross spokeswoman in the rebel headquarters of Benghazi.

Early Tuesday, planes and explosions were heard over Tripoli, and the Libyan government took journalists to the site of a library and school that it said had been bombed by NATO. It was the same site that had been bombed just over a week ago and is 50 yards from a large communications tower, which was not hit.

Two hours later, planes could again be heard clearly in the city, along with at least five blasts. The raid apparently hit a government office building next door to a hospital in central Tripoli. The hospital sustained blown-out windows and damaged ceilings. It was unclear if the strikes had hit elsewhere in the city.

Special correspondent Portia Walker in Benghazi, Libya, contributed to this report.