Sections of two telecom cables were cut on November 17 and 18 in Swedish territorial waters of the Baltic Sea.

Suspicions have been directed at a Chinese ship -- the Yi Peng 3 -- which according to ship tracking sites had sailed over the cables around the time they were cut.

The Yi Peng 3 has remained anchored in the Kattegat strait between Sweden and Denmark since November 19.

"Representatives of the Chinese authorities are conducting investigations aboard the vessel and have invited the Swedish authorities to take part in an observer role," Swedish police said in a statement Thursday.

It added that "no investigative measures will be taken by the Swedish Police Authority aboard the vessel".

Police stressed that the "investigations taking place on the vessel on Thursday are not part of the police investigation".

Police also said the visit was facilitated by Danish authorities and that the Swedish Accident Investigation Authority (SHK) would also take part.

Danish Foreign Minister Lars Lokke Rasmussen told Danish media that representatives from four countries -- China, Sweden, Germany and Finland -- were aboard the ship.

Rasmussen added that a Danish representative was also there "due to the facilitating role we have played", referring to meetings held between the country at the foreign affairs ministry in Copenhagen earlier this week.

"It is our expectation that once the inspection is completed by this group of people from the four countries, the ship will be able to sail to its destination," Rasmussen said.

- International waters -

The SHK noted in a separate statement that the ship had "anchored in international waters", where "Swedish authorities are not able to exercise jurisdiction over a foreign vessel".

John Ahlberk, director of SHK, told AFP that they had three investigators aboard, and were hoping to gather "as much information as possible".

"There have been claims that the cable breakage has to do with anchors from the ship. So it is interesting for us to hear what the crew has to say about it," he said.

Ahlberk noted however that it was not clear to what extent they would be able to speak to the crew or conduct their own investigations since the investigation was led by Chinese authorities aboard a Chinese ship.

European officials have said they suspect sabotage linked to Russia's invasion of Ukraine.

The Kremlin has rejected the comments as "absurd" and "laughable".

Sweden in late November requested China's cooperation in the investigation, but Prime Minister Ulf Kristersson stressed that there was no "accusation" of any sort.

Early on November 17, the Arelion cable running from the Swedish island of Gotland to Lithuania was damaged.

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

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

In September 2022, a series of underwater blasts ruptured the Nord Stream pipelines that carried Russian gas to Europe, the cause of which has yet to be determined.

In October 2023, an undersea gas pipeline between Finland and Estonia was shut down after it was damaged by the anchor of a Chinese cargo ship.