Russia is taking security measures as a precaution against the possibility that tension over North Korea could escalate into nuclear war, officials said Wednesday.

The standoff triggered by Pyongyang's nuclear test on Monday could affect the security of Russia's far eastern regions, which border North Korea, a security source told Interfax.

"The need has emerged for an appropriate package of precautionary measures," the unidentified source said. "We are not talking about stepping up military efforts but rather about measures in case a military conflict, perhaps with the use of nuclear weapons, flares up on the Korean Peninsula." The official did not elaborate further.

North Korea has responded to international condemnation of its nuclear test and a threat of new UN sanctions by saying it is no longer bound by an armistice signed with South Korea at the end of the 1950-53 Korean War.

A Russian Foreign Ministry official said the "war of nerves" over North Korea should not be allowed to grow into a military conflict, a reference to Pyongyang's decision to drop out of the armistice deal, Itar-Tass reported.

"We assume that a dangerous brinkmanship, a war of nerves, is under way, but it will not grow into a hot war," the official said. "Restraint is needed."

The Foreign Ministry summoned North Korea's ambassador and expressed "serious concern" over the test.

Russia is a veto-wielding, permanent member of the UN Security Council, which is preparing to discuss the latest standoff over the peninsula.

In the past, Moscow has been reluctant to support Western calls for sanctions. But Russian officials in the United Nations have said that this time, the authority of the UN is at stake.

President Dmitry Medvedev told South Korean President Lee Myung-bak, who called him on Wednesday, that Russia was prepared to work with Seoul on a new UN Security Council resolution and to revive international talks on the North Korean nuclear issue.