The Swedish National Seismic Network (SNSN) said Tuesday that it had detected two explosions on Monday near the Nord Stream pipelines.
The first explosion was recorded at 2:03 a.m. local time in the early hours of Monday and the second one 17 hours later, at 7:04 p.m. on Monday evening, according to SNSN.
SNSN said that one of the underwater explosions resulted in a tremor of 2.3 magnitude.
According to SNSN, the last time a similar seismological event was registered in the area was in 2016. It added that this area is not usually used for defense exercises.
The German geological research centre, GFZ, told CNN that two tremors were registered at similar times at a seismic station on the Danish island of Bornholm, again close to the reported leaks on the pipelines.