MOSCOW (Reuters) - Russia urged South Korea on Friday to halt plans for an artillery drill that North Korea had said hours earlier would prompt a new strike at the South.

Stepping up diplomatic efforts, Russia’s Foreign Ministry summoned the South Korean and U.S. ambassadors to express “extreme concern” over plans for a live-firing drill set to begin on Saturday on an island near a disputed maritime border.

“The Russian Federation insistently calls on the Republic of Korea to refrain from holding the planned firing of artillery in order to prevent the further escalation of tensions on the Korean peninsula,” the Foreign Ministry said.

Deputy Foreign Minister Alexei Borodavkin repeated the message in a meeting with the South Korean and American ambassadors in Moscow, the ministry said in a statement. It said U.S. military officers were to observe the Dec 18-21 drill.

Russia said a similar drill on Nov 23 had “provoked an exchange of fire ... that caused casualties,” echoing Pyongyang’s assertion that its shelling of Yeonpyeong island was a response to what Seoul said was a routine artillery drill.

North Korea said earlier on Friday that it would strike again, with an even stronger response than the shelling that killed four people last month, if Seoul goes ahead with its planned live-firing drill on the island.

The Russian statement marked a shift to a tougher line on South Korea’s military drills.

When Russian Foreign Minister Sergei Lavrov met his North Korean counterpart on Monday, Lavrov said military exercises had added to tension but also that the North’s shelling of the island deserved condemnation, according to the ministry.

On Friday, the Russian ministry expressed “deep concern” about South Korea’s planned drill and said it was “extremely important” to ease tension between the two Koreas, restore dialogue and resolve all disputes without using force.

Russia, which shares a short border with North Korea, has put its forces in the nation’s far east on alert because of the Korean tension, the Interfax news agency cited the chief of the military General Staff as saying on Tuesday.

Russia was one of the participants in long-suspended six-nation talks over North Korea’s nuclear program. North Korea was a beneficiary of Moscow’s largesse during the Cold War, but China now has more influence with Pyongyang.