Western media reports on the blowing-up of the Nord Stream gas pipelines are a coordinated bid to divert attention and Russia is perplexed that U.S. officials can assume anything about the attacks without an investigation, the Kremlin said today.

The New York Times, citing intelligence reviewed by U.S. officials, reported on Tuesday that a pro-Ukraine group- likely made up of Ukrainians or Russians - was responsible for blowing up the Nord Stream gas pipelines that run under the Baltic Sea between Russia and Germany last September.

Germany's ARD broadcaster and Die Zeit newspaper said the attack was carried out by five men and one woman who rented a yacht and used false passports.

"Obviously, the authors of the attack want to divert attention," Kremlin spokesman Dmitry Peskov told the state RIA news agency, adding that the information had been planted.

"How can American officials assume anything without an investigation?"

"The very least that the Nord Stream shareholder countries and the United Nations must demand is an urgent, transparent investigation with the participation of everyone who can shed light," Peskov said.

The Nord Stream 1 shareholders are Russia's state energy firm Gazprom, Germany's Wintershall DEA AG and E.ON, Dutch company NV Nederlandse Gasunie and France's Engie.

Gazprom is the sole shareholder in the parallel Nord Stream 2 pipeline, which was constructed with financing from Wintershall DEA, Engie, Austria's OMV, Shell and Germany's Uniper.

Russia has repeatedly complained about being excluded from European probes into the explosions.

"We are still not allowed in the investigation. Only a few days ago we received notes about this from the Danes and Swedes," Peskov said.

"This is not just strange. It smells like a monstrous crime."

The undersea explosions, seven months into the Russia-Ukraine conflict, occurred in the exclusive economic zones of Sweden and Denmark in the Baltic Sea. Both countries have concluded the blasts were deliberate, but have not said who might be responsible.

Russia, without providing evidence, has at various times accused Britain and the United States of blowing up the pipelines, which they deny.

The ruptured pipelines are set to be sealed up and mothballed as there are no immediate plans to repair or reactivate them, sources familiar with the plans have told Reuters.