ATHENS, Greece >> Greece is sending a navy frigate and a helicopter to locate a cargo ship believed to be carrying hundreds of migrants in the northern Ionian Sea after authorities received a distress call from someone on board the ship, authorities said.

The ship, the Moldovan-flagged Blue Sky M, was sailing in poor weather near the tiny island of Othonoi, northwest of Corfu. A merchant marine ministry official said the distress call had come from one of the passengers on board the ship.

The ship is believed to be carrying about 400-600 migrants.

The official spoke on condition of anonymity because no official information had yet been issued.

The incident comes two days after a Greek passenger ferry with more than 400 people on board caught fire in the same area, leading to a huge rescue operation by Italian and Greek coast guard and military officials. At least 10 people died in that incident, while more than 400 were rescued.

Authorities are still searching for potential missing passengers from the Norman Atlantic ferry.

The Greek frigate Navarino, which is heading to locate the cargo ship, had been in the area assisting in the rescue operation for the Norman Atlantic.