Estonia has begun naval patrols to protect a cable supplying electricity from Finland following suspected sabotage of another one on Christmas Day, Defence Minister Hanno Pevkur has said.

"We've decided to send our navy close to Estlink 1 to defend and secure our energy connection with Finland," he posted on X on Friday.

The Estlink 2 submarine cable was disconnected from the grid on Wednesday, just over a month after two telecommunications cables were severed in Swedish territorial waters in the Baltic Sea.

Finnish authorities said on Thursday that they were investigating an oil tanker that sailed from a Russian port over the suspected "sabotage".

The Eagle S vessel, which flies under the flag of the Cook Islands in the South Pacific, was en route to Port Said in Egypt.

'Hard to believe they are accidents'

"The assumption at the moment is that it is a shadow fleet vessel and the cargo was unleaded petrol loaded in a Russian port," said Sami Rakshit, director general of Finnish Customs.

The shadow fleet refers to ships that transport Russian crude and oil products that are embargoed due to Russia's war with Ukraine.

Police suspect that the oil tanker's anchor might have damaged the power cable.

Estonia's Foreign Minister Margus Tsahkna said on Thursday: "The damages to critical underwater infrastructure have become so frequent that it's hard to believe they are accidents or just bad maritime manoeuvres."

Dragging an anchor on the seafloor can hardly be considered an accident, Tsahkna added.

Authorities in the region have been on high alert for potential acts of sabotage following a string of outages of power cables, gas pipelines and telecom links in the Baltic Sea in recent years, although subsea cables are also subject to technical malfunctions and outages caused by accidents.

On November 17 and 18, two undersea telecom cables in the Baltic Sea were damaged, immediately prompting European officials to claim that it was an act of sabotage.

The telecom cables, which connect Lithuania with Sweden and Finland with Germany were damaged around the same time when a Chinese vessel, Yi Peng 3, was reportedly seen in the vicinity.

China has shown willingness to cooperate in the probe so far seems to undermine the Western allegations of sabotage.

The Nord stream

This is not the first time European and American officials have pinned the blame of sabotage on Russia or China.

The West accused Russia of a sabotage attack on Nord Stream gas pipelines in 2022. But later it was revealed by the German investigation that the attack was carried out by a Ukrainian team.

Berlin even issued an arrest warrant for a Ukrainian diver believed to be hiding in Poland.

The Wall Street Journal in its investigative report held Ukraine responsible for blowing up the Nord Stream 1 and 2 pipelines in September 2022.

It also mentioned that Poland has long maintained that its security interests have been harmed by Nord Stream.