Russia's spy chief on Friday blamed the West for what he said was the "terrorist act" of wrecking the subsea Nord Stream pipelines, raising the temperature in a crisis that has left Europe racing to secure its energy infrastructure and supplies.

Sergei Naryshkin, the director of Russia's Foreign Intelligence Service (SVR), said the West was trying to cover up who carried out an attack on the gas pipelines under the Baltic Sea, while the Kremlin demanded an international probe.

European Union states, once heavily reliant on Russia and now trying to find alternative gas supplies, say they believe leaks were caused by sabotage, but have stopped short of naming anyone. They are racing to secure other energy infrastructure.

"The West is doing everything to hide the true perpetrators and organizers of this international terrorist act," Naryshkin said.

The Nord Stream pipelines, which were not pumping gas to Europe when the leaks were found but had gas in them, have been flashpoints in an energy standoff between the West and Russia since its invasion of Ukraine, fuelling a cost-of-living crisis.

The Russian accusation, the most direct to date by a Russian official, is likely to be strongly resisted by European countries. The United States, which has said it was too early to confirm it was sabotage, has dismissed talk it was responsible.

The European Union is still investigating how Russia's Nord Stream 1 and Nord Stream 2 pipelines burst this week, draining gas into the Baltic Sea off the coast of Denmark and Sweden. Seismologists registered explosions in the area.

Map: Leaks reported from Russian Nord Stream pipelines

WIDER CONFLICT

The pipeline incident has prompted European countries to step up vigilance over other critical infrastructure, which looks suddenly much more vulnerable.

Poland's electricity grid operator on Friday announced checks on an undersea cable carrying power from Sweden that crosses the damaged Nord Stream pipelines.

There is also heightened focus on the Baltic Pipe, a project that was unveiled this week. A rival to the Nord Stream network, the Baltic Pipe will transport gas to the Danish and Polish markets and end-users in neighbouring countries from Oct. 1.

"The risk to near-term gas flows has risen sharply on fears that further sabotage could occur on critical gas import pipelines," said a note from Fitch Solutions, citing the Baltic Pipeline.

"The possibility of additional acts of sabotage on critical infrastructure is a growing risk that would raise the risk of tipping the war into a wider regional conflict."

Norway, a major Russian rival on gas supplies, will deploy its military to protect oil and gas installations against possible sabotage after warnings of unidentified drone sightings in September.

Germany's energy regulator called in a Reuters interview for more protection for critical energy infrastructure.

With no gas flowing through Nord Stream for the foreseeable future, European countries are racing to secure more energy supplies and trying to cushion households from an explosion in prices since last year.

European Union countries on Friday agreed to impose emergency levies on energy firms' windfall profits and began more fraught talks on imposing a bloc-wide gas price cap.

Germany on Thursday unveiled a 200 billion euro relief package for companies and citizens, in what Chancellor Olaf Scholz's government characterised as a forceful response to what it called Russia's "energy war" against Europe.