One of the biggest disasters at sea resulting in more than 800 peoples deaths, largest tragedy at sea since Titanic .

In a joint statement on Monday, Estonian, Swedish and Finnish foreign ministers announced they would "assess the new information."

A total of 852 people drowned when the passenger and car ferry sank in Finnish waters in the early hours of September 28, 1994, while en route from Tallinn to Stockholm in Europe's worst peacetime shipping disaster.

In 1997, investigators concluded the disaster was caused by the bow door of the ship being wrenched open in heavy seas, allowing water to gush into the car deck.

Survivors and relatives of those killed have fought for over two decades for a fuller investigation, with some claiming that the opening of the bow visor would not have caused the vessel to sink as quickly as it did.

The ship went down in just one hour, leaving only 137 survivors.

The makers of the Discovery Networks documentary "Estonia: The Find That Changes Everything" discovered the hole when they explored the wreckage with a remote-controlled submarine.

Experts told the filmmakers that only a massive external force would be strong enough to cause the rupture, raising many questions about what really happened that night.

"I believe the truth is something other than what people have been told until now," survivor Carl Eric Reintamm told the programme.

Survivors described hearing a loud bang and Reintamm said he saw a large white object in the water next to the ferry, testimony which experts interviewed in the programme said has not been taken into account before now.

- Exploration was prohibited until recently -