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 near Corfu 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.
Authorities said the distress call had come from one of the passengers on board the ship, which warned of "suspected armed people", Reuters reports.
The ship is believed to be carrying about 600 migrants.
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.
One man died trying to escape the ship and a further nine bodies were later found.
Two Albanian sailors were also killed on a tug boat during an operation to secure the fire-stricken Greek ferry.
Authorities are 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.
But Italian officials still cannot confirm the number of people missing from the ferry.
Survivors described the "scenes from hell" as passengers trampled over each other to get to safety before the rescue operation was launched.
Italian prosecutors have opened a criminal investigation into the fire, the cause of which is still unknown.