Moscow on Wednesday questioned whether Washington had caused mysterious leaks in undersea gas pipelines in Europe, which it blamed on sabotage, which US officials bluntly called ridiculous as Russia opened a “terrorism” probe.

The three outflows from Russia-Germany’s Nord Stream 1 and 2 pipelines have pushed up natural gas prices and exacerbated an energy crisis in Europe as winter approaches, while also stoking geopolitical tensions.

Swedish intelligence announced it would launch an investigation into the massive leaks in the Baltic Sea, branding it “serious sabotage” hours after the EU described the damage as a “premeditated act”.

Russia’s FSB security service said it had launched an investigation into “international terrorism,” Russian prosecutors said, citing “premeditated actions” to damage the pipelines.

Amid the claims and counter-claims, the UN Security Council said it would meet on Friday – at Russia’s request – to discuss the leaks.

“As the current President of the Security Council, France, informed us today, Russia has asked for a meeting on the Nord Stream leaks and this meeting is scheduled for Friday,” Sweden’s Foreign Minister Ann Linde said at a press conference.

Russian representative Dmitry Polyanskiy said the meeting will take place at 3 p.m. (1900 GMT) at the UN headquarters in New York.

Questions over who is to blame have prompted high-level finger pointing, with Moscow accusing the United States that Nord Stream 2 would be “done” if Russia invaded Ukraine.

President Joe “Biden has an obligation to answer the question of whether the US has carried out its threat,” State Department spokeswoman Maria Zakharova said on social media.

Washington dismissed the suggestion, with a National Security Council spokeswoman saying, “We all know that Russia has a long history of spreading disinformation and is doing it again here.”

Among Western allies, suspicion about the leaks has focused on Russia, which has cut off gas supplies to Europe in retaliation for tough Western sanctions over the war in Ukraine.

They are “no coincidence,” said EU foreign policy chief Josep Borrell. “All available information indicates that these leaks are the result of a deliberate act.”

He warned: “Any intentional disruption of Europe’s energy infrastructure is absolutely unacceptable and will be met with a robust and unified response.”

EU leaders Ursula von der Leyen and Charles Michel have also blamed sabotage for the Nord Stream leaks, as have leaders of several European countries.

Michel tweeted that they “appear to be an attempt to further destabilize the EU’s energy supply”.

He added: “Those responsible will be held fully accountable and asked to pay.”

The EU is currently considering further sanctions against Russia over votes to annex four regions in Ukraine occupied by Moscow’s armed forces.

None of the Nord Stream pipelines are currently operational, but they were full of gas when they were hit by “massive releases of energy,” Swedish seismologists said.

One of the seismologists told AFP, “There isn’t much other than an explosion that could cause this.”

Denmark said more than half of the gas in the Nord Stream pipelines has now leaked into the atmosphere, adding the rest will likely escape by Sunday, as Defense Minister Morten Bodskov said the pressure from the leak meant it was ” a week or two” before inspections of the damaged structures could begin.

Two Danish military ships were sent to the affected area.

According to climate associations, Nord Stream 1 and 2 contained around 350,000 tons of natural gas – methane and Greenpeace estimate the leaks could result in the release of almost 30 million tons of CO2, or more than two-thirds of Denmark’s annual emissions.

Following allegations of sabotage by Europe, fossil-fuel-rich Norway – which has overtaken Russia as Europe’s largest supplier of gas – has tightened the security of its oil and assets in response.

“The government has decided to take measures to increase security at infrastructure sites, land terminals and platforms on the Norwegian continental shelf,” said Norway’s Energy Minister Terje Aasland.

The Norwegian Petroleum Safety Authority earlier this week called for “increased vigilance from all operators and shipping companies on the continental shelf”.

Built parallel to the Nord Stream 1 pipeline, Nord Stream 2 should double the capacity for Russian gas imports to Germany.

But Berlin blocked the newly completed Nord Stream 2 in the days leading up to the war.

Germany, which has been heavily dependent on fossil fuel imports from Russia for its energy needs, has since come under acute pressure as Moscow’s supplies dwindle.