The new inspections were initiated at the behest of the navy itself and are independent of the ongoing Swedish criminal investigation into the leaks.

"We have felt a need to complement the inspection we did there earlier," Jimmie Adamsson, a spokesman for Sweden's navy, told AFP.

The navy declined to give details of the steps they are taking or hat specifically they are looking for.

The new inspections, which began on Monday, should be completed within a week.

The four leaks emerged on the two Nord Stream pipelines in the Baltic Sea off the coast of the Danish island of Bornholm at the end of September with seismic institutes reporting that they had recorded two underwater explosions prior to the leaks appearing.

While the leaks were in international waters, two of them were in the Danish exclusive economic zone and two of them in the Swedish.

Swedish authorities announced in early October that they had conducted an underwater inspection of the site and collected "pieces of evidence", and that the inspection backed up suspicions of sabotage.

The pipelines, which connect Russia to Germany, have been at the centre of geopolitical tensions as Russia cut gas supplies to Europe in suspected retaliation to Western sanctions over Moscow's invasion of Ukraine.

Although they were not in operation when the leaks occurred, they both still contained gas which spewed up through the water and into the atmosphere.