VALLETTA, Malta –  The U.N. refugee agency says Syrian survivors of the latest shipwreck involving migrants in the Mediterranean claim Libya's coast guard fired on their boat.

The UNHCR has asked Libya for an explanation. Libyan Prime Minister Ali Zidan denied the allegations in a press conference Sunday.

UNHCR spokeswoman Melissa Fleming said Monday from Geneva that survivors said their boat was fired on a couple of hours after leaving Zwara, Libya.

She says survivors told the agency that the shooting damaged the ship's hull, possibly contributing to the sinking, and injured four people.

The vessel sank 65 miles south of the Italian island of Lampedusa in Malta's search-and-rescue area. Authorities say 34 people died; more than 200 were rescued.

Survivors have told the U.N. that 400 to 500 people were on board.