Nevertheless, the efforts continued on Thursday. “There is no plan to stop the search,” Nikolaos Alexiou, a spokesman for the Greek Coast Guard, told state television. “We’re continuing and the search will broaden.”

The survivors will be moved to a state camp in Malakasa, north of Athens, as soon as processing by coast guard officials has been completed, the migration ministry said. The authorities were questioning several people from the ship who were believed to be smugglers, state television reported.

The survivors, all men, are believed to be from Syria, Egypt and Pakistan. It remained unclear how many women and children might be among the missing.

The tragedy unfolded as Greece is preparing for a general election on June 25, and it has prompted political leaders to suspend campaigning as a caretaker government announced three days of national mourning.

The migration issue is already very sensitive in Greece, especially in light of the government’s tactics aimed at deterring migration, an approach that has widespread support but has been roundly criticized by rights groups.

Greece is a major destination for migrants trying to make their way to Europe, and the sinking was the deadliest such episode off its coast since before 2015, when 70 people died after a boat carrying migrants sank near the island off Lesbos, according to the International Organization for Migration.