As the trial into the Eagle S tanker incident begins at Helsinki District Court, a key question has emerged: should the crew have noticed that the ship's anchor was dragging behind the vessel for 90 kilometres?

Finnish prosecutors allege the Eagle S tanker dragged its anchor along the seabed, damaging five undersea cables between Finland and Estonia.

The Georgian captain of the vessel, Davit Vadatchkoria, told Yle's Swedish-language unit that the Eagle S crew had not noticed the anchor dragging along the seabed.

This is the first time the captain has shared his account of what transpired in the waters of the Finnish Gulf last Christmas. Staying in Helsinki under a travel ban, Yle has spoken to the captain several times since the spring.

Captain critical of Finnish authorities

The Estlink 2 power cable between Finland and Estonia stopped working on Christmas Day last year. Finnish authorities carried out a command-style boarding operation late in the evening on the same day to stop the tanker, which had run over the cable earlier that afternoon.

Vadatchkoria said he knew Finnish authorities had only limited powers to issue orders to commercial vessels in international waters. Still, he chose to comply with the instructions of the Finnish Coast Guard vessel Turva and anchor in Finnish territorial waters.

"The Turva was armed. Why would I have risked my crew, my ship, and my cargo? I had no reason to try to escape," Vadatchkoria said.

According to Vadatchkoria, armed authorities, who he claims lacked prior experience in seizing a tanker, could have caused a disaster by dropping down from helicopters in full combat gear.

He pointed to strict rules on an oil tanker's deck to prevent static electricity that could cause sparks.

"It was a serious breach of maritime safety. We followed all their orders. They had no reason to be so aggressive," he said, adding that the Finnish authorities did not say why they had boarded his ship.

Finnish officials confiscated electronic devices, computers, cameras and phones from the Eagle S.

Trial starts

The captain, first and second officers of the Cook Islands-registered Eagle S tanker face a slew of charges concerning the incident. The trial is set to begin on Monday at Helsinki District Court.

The charges include aggravated sabotage and aggravated telecommunications interference, as well as lesser offences such as vandalism and endangering public safety.

Deputy Prosecutor General Jukka Rappe has alleged the actions of the Eagle S tanker crew were intentional, meaning they were carried out deliberately.

Davit Vadatchkoria disagrees.

But the question remains: should the crew have spotted the anchor dragging for 90 kilometres?

Yes, according to the prosecution. No, says the captain, who adds that severe weather at the time played a role.

Vadatchkoria also told Svenska Yle that the court must first determine whether he and two others can even be prosecuted in Finland, since the incident occurred outside Finnish territorial waters.

While the Eagle S has been understood to be a part of Russia's sanctions-busting shadow fleet, Vadatchkoria asserts that the case file contains no evidence to support claims of intentional misconduct. Authorities have confirmed that no Russian espionage equipment was discovered aboard the Eagle S tanker.

Rappe has meanwhile said that there is no evidence pointing to a conspiracy behind the Eagle S tanker incident. This can be interpreted as the authorities not finding any financial transactions from the Kremlin or any communications indicating that the Eagle S was on a mission to damage undersea cables to destabilise the Nordic and Baltic regions.

Vadatchkoria claims the Finnish leadership was aware of the Eagle S dragging its anchor as early as 3:02pm on the day of the incident.

"They could have told us to raise the anchor, but instead, they tracked our route for hours without stepping in."

The National Bureau of Investigation (NBI) declined to comment on the captain's allegations.