Members of the United Nations Security Council have expressed concerns about a new treaty signed between Russia and North Korea that strengthens bilateral military cooperation.

The council convened an emergency meeting on Friday at the request of Japan, the United States and other countries.

The new treaty between Moscow and Pyongyang stipulates that if either of them is placed under a state of war, the other will provide military and other assistance.

UN Under-Secretary-General and High Representative for Disarmament Affairs Nakamitsu Izumi noted that the transfer of weapons from North Korea violates Security Council resolutions.

She said all countries, including Russia, "must fully abide by the relevant Security Council sanctions" on North Korea.

Japan's UN Ambassador Yamazaki Kazuyuki said Japan "condemns in the strongest possible terms" North Korea's export of ballistic missiles to Russia in violation of relevant Security Council resolutions, as well as Moscow's use of those missiles in Ukraine. He added that the transfer of these weapons will "exacerbate the situation in Ukraine."

Russia's ambassador to the UN, Vassily Nebenzia, called the speculation about Russia using North Korean missiles in Ukraine untrue.

Nebenzia also said the Russia-North Korea treaty is "intended to play a stabilizing role in North-East Asia against the background of an unprecedented escalation of tension."

He criticized the US for increasing its military activity in the region.

North Korea's UN envoy, Kim Song, echoed the view. He said there is no reason to be concerned about this treaty if there is no intention to invade North Korea and Russia.