The Netherlands has denied a Russian claim that a mystery submarine that the Swedish military has been looking for could be Dutch.

The Swedish military launched a major search operation late on Friday after sightings of an unidentified vessel around islands off Stockholm.

A Russian defence ministry official suggested this morning that the vessel could be the Dutch Bruinvis, which had taken part in exercises off the coast of Sweden.

"To remove tensions in the waters of the Baltic Sea and to save money of the Swedish taxpayers we would recommend [Sweden] to turn to the naval command of the Netherlands for an explanation," a source told Russian news agencies.

The source said the Dutch diesel-electric submarine was carrying out tasks near Stockholm last week.

It was in the Estonian capital of Tallinn on Friday and was expected to return today, the source said.

Swedish media reported over the weekend that a Russian U-boat might be in trouble around islands off Stockholm.

However, the Swedish military said yesterday that it was not possible to determine the nationality of the vessel.

The Dutch defence ministry said its submarine was no longer in the area when the mystery vessel was reportedly sighted.

"We participated in an exercise with Sweden with several ships, but it ended last week Thursday," Dutch defence ministry spokeswoman Marnoes Visser told AFP.

"The Bruinvis then departed for Estonia, where it has been at anchor in the Tallinn harbour over the weekend."

The Bruinvis was now making its way back to the Netherlands, Ms Visser added.

"The Dutch submarine is not involved and we are further not involved in any search action or such," she said.

Swedish Rear-Admiral Anders Grenstad said yesterday the armed forces were carrying out an intelligence operation to establish the presence of a foreign vessel. 

The Russian defence ministry was not available for comment.