Finnish police believe the vessel's six-tonne anchor struck the Balticconnector pipeline between Finland and Estonia in October 2023, leading to damage and the anchor breaking off.

The pipeline's operator said at the time it would take at least five months to repair the damage, leaving Finland dependent on liquefied natural gas imports for the winter.

The incident came just over a year after underwater explosions hit three gas pipelines in the Baltic Sea, cutting off a major supply route to Europe from Russia.

An anchor recovered from the seabed likely belonged to the 169-metre-long (554-foot) vessel Newnew Polar Bear, Finnish authorities said at the time.

The ship's captain, 43-year-old Chinese national Wan Wenguo, has been in custody in Hong Kong since May 2025, accused of causing "criminal damage".

Wan was "reckless" and "damaged property belonging to another" without lawful excuse, according to the charge sheet seen by AFP.

He faces up to two years in prison for the criminal damage charge, according to his lawyer.

Wan also pleaded not guilty to two summons charges of failing to ensure the ship complied with safety requirements.

Wan did not apply for bail, with the case adjourning until May 5.