Sections of the two telecom cables, both in Swedish waters of the Baltic Sea, were cut on Sunday and Monday.

Denmark's navy said Wednesday that it was shadowing a Chinese cargo vessel, the Yi Peng 3, that had sailed over the cables around the time they were severed, according to ship tracking sites, though there is nothing yet to indicate that it was involved in the incidents.

European officials have said they suspect "sabotage" and "hybrid warfare" linked to Russia's invasion of Ukraine, which the Kremlin has rejected as "absurd" and "laughable".

The fact that the ship remains anchored in the narrow Kattegat strait between Sweden and Denmark since Tuesday has raised questions.

"Denmark does not own the damaged cables, and the ship is currently in international waters," the Danish foreign ministry told AFP in a statement Thursday.

This limits the Danish authorities' possibility to intervene.

"The foreign ministry has had a string of diplomatic contacts, but can not go into any concrete details," it said.

China's foreign ministry on Monday denied any responsibility in the matter.

Sweden and Finland have opened police investigations, and German police are supporting them.

Swedish police said Wednesday that they were interested in a ship that had been observed in the vicinity of the cables, but did not identify the vessel.

The C-Lion 1 submarine cable connecting Helsinki and the German port of Rostock was cut Monday south of Sweden's Oland island, around 700 kilometres (435 miles) from Helsinki.

Early Sunday, the Arelion cable, running from the Swedish island of Gotland to Lithuania, was also damaged.

Tensions have mounted in the Baltic Sea region since Russia's invasion of Ukraine in February 2022.