"The Italian authorities have confirmed that four bodies have been recovered," Maritime Minister Miltiadis Varvitsiotis told reporters.
At least one passenger – a Greek national who apparently fell into the water while trying to reach a lifeboat – was previously confirmed to have died as a result of the disaster.
Overall, 391 people have been rescued from the ferry that was carrying 478 passengers and crew, Varvitsiotis said.
Prosecutors in the Italian port of Bari on Monday opened a criminal investigation into how the Norman Atlantic caught fire at sea and whether negligence contributed to the disaster.
The investigation will seek to establish how the fire started and why it was able to gain such force that passengers feared they would be burned alive or suffocated by thick smoke.
The Italian owner of the boat has insisted that the vessel was in full working order and had passed a technical inspection which included its firedoors on December 19th.
One of the first survivors to arrive in Italy on Monday has alleged that the staff were clearly unprepared for dealing with an emergency and appeared to be unaware of how to organise an evacuation.