Bad weather in the Adriatic Sea is thwarting efforts to tow a fire-ravaged ferry to Italy, so authorities can search it for more possible dead and investigate the cause of the blaze that killed at least 11 people.

Bari prosecutor Giuseppe Volpe was quoted as saying the Norman Atlantic ferry was attached to a tug but towing was not immediately possible. He told the ANSA news agency that 98 people are still unaccounted for. It's not clear if they ever boarded the ferry or perhaps died in the fire or the sea.

A pre-dawn fire raced Sunday through the ferry, which left Greece on Saturday bound for Italy. Hundreds of survivors have been rescued but the exact number is not known. A cargo ship brought dozens more Wednesday to Italy.