Explosions were registered by seismologists in Sweden over the last 36 hours, according to the country’s national broadcaster SVT, in the same areas where gas leaks were reported to have occurred at the Nord Stream 1 and 2 pipelines yesterday, stoking fears that the projects were sabotaged.

“SVT can reveal that measuring stations in both Sweden and Denmark registered strong underwater explosions in the same area as the gas leaks on Monday,” SVT reported. Bjorn Lund, a lecturer in seismology at the Swedish National Seismic Network, SNSN, was quoted by the broadcaster as saying “there is no doubt that these are explosions.” The first blast was recorded at 02:03 in the early morning of September 26, and the second at 19:04 in the evening.

Germany’s government considers sabotage a likely cause of the leaks, according to a report by national daily Tagesspiegel on September 27, while the Kremlin has said it cannot rule out sabotage as a possibility. Denmark’s prime minister Mette Frederiksen has said the same.

The Kremlin also did not rule out foul play. Kremlin spokesman Dmitry Peskov said the two gas pipelines could be sabotaged.

"Now we can't rule out any option," he told reporters responding to a relevant question from TASS. "Obviously, there is some kind of destruction of the pipe, and as for what caused it, before the results of the research appear, we cannot rule out any single way," he added.

Peskov stressed that "certainly, this is an issue related to the energy security of the entire continent."

Meanwhile, Ukraine has already blamed Russia, with Mikhaila Podolyak, head of the office of Ukraine’s president, describing it as “an act of aggression towards the EU.” “Russia wants to destabilise the economic situation in Europe and cause pre-winter panic,” he tweeted.

Denmark’s armed forces have released a video showing methane bubbles boiling up to the surface of the sea, with the largest leak causing a surface disturbance of well over a 1 km in diameter.

The Danish Energy Agency meanwhile estimates that it could take a week for the gas to stop draining out of Nord Stream 2. While the pipeline has never flowed gas commercially, it was nevertheless filled with methane last year as part of pre-commissioning work. Likewise Nord Stream 1, even though it halted gas flow at the end of August, would still have been full of gas in order to maintain pressure. According to Nord Stream 1’s operator, three of the four strings that make up the two pipelines have suffered leaks, describing the damage as “unprecedented.”

While European gas prices did not respond to initial reports of the gas leaks, they are currently up close to 7% on the previous trading price, at €185/MWh.