STOCKHOLM, Sept 29 — A fourth leak has been detected in undersea pipelines running from Russia to Europe, the Swedish Coast Guard said Thursday, after explosions were reported earlier this week in suspected sabotage.

"There are two leaks on the Swedish side and two leaks on the Danish side,” a Swedish Coast Guard official said, after three leaks were confirmed earlier this week on the Nord Stream pipelines in the Baltic Sea.

The official added that the two leaks on the Swedish side are "close to each other”.

The Swedish coast guard could not immediately say why the latest leak only appeared days after the initial breaches.

Media reported that the latest leak was detected at the Nord Stream 2 pipeline, but the coast guard did not confirm this.

Sweden had previously reported a leak on the Nord Stream 1 pipeline northeast of Bornholm, while Denmark has confirmed a leak on Nord Stream 2 to the southeast of the island, and another to the northeast above Nord Stream 1.

The vast leaks cause significant bubbling at the surface of the sea several hundred metres wide, making it impossible to immediately inspect the structures.

Suspicions of sabotage emerged after the leaks were detected. Moscow denied it was behind the explosions, as did the United States, saying Moscow’s suggestion it would damage the pipeline was "ridiculous”.

The UN Security Council will meet Friday to discuss the incident.

The Nord Stream 1 and 2 pipelines, which link Russia to Germany, have been at the centre of geopolitical tensions in recent months as Russia cut gas supplies to Europe in suspected retaliation against Western sanctions following Moscow’s invasion of Ukraine.

While the pipelines — operated by a consortium majority-owned by Russian gas giant Gazprom — are not currently in operation, they both still contained gas. — AFP