Blasts monitored in the area of the Barents Sea where
a Russian nuclear submarine sank in August came from depth charges and grenades launched from a Russian flagship moored at the site, a navy spokesman said on Wednesday.
A Northern Fleet official said that depth charges and grenades were used routinely to ensure security of ships patrolling the area.
"All countries in the area and fishing companies have been advised about the operation in advance and it is completely safe as far as ecology is concerned," he said.
In Oslo, the Norwegian Norsar seismological observatory said on Wednesday it had detected about 40 explosions near the sunken submarine Kursk, in what could be a Russian campaign to deter foreign submarines from snooping around the wreck.