Russia has hit out at a US-led effort to increase international pressure on North Korea, saying it was making the situation worse and undermining the United Nations.

Twenty nations hosted by the United States and Canada in Vancouver agreed yesterday to consider tougher sanctions to press North Korea to give up its nuclear weapons.

North Korean leader Kim Jong Un has refused to give up development of nuclear missiles capable of hitting the US, in spite of increasingly severe UN sanctions, raising fears of a new war on the Korean peninsula.

The Russian Foreign Ministry said top diplomats from Russia and China had not been invited to the meeting, which was made up of countries that backed South Korea during the 1950-53 Korea War, and that the events were damaging the authority of the UN.

"It is an absolutely unacceptable situation, when 17 countries take upon themselves the role of 'helper' to the UN Security Council and interpreter of its resolutions, thereby actually putting its authority into doubt," the ministry said in a statement.

"Such events, conducted hastily and to the detriment of functioning multilateral formats, are not contributing to the normalisation of the situation around the Korean peninsula, but on the contrary, aggravating it."

In Washington, a senior US official said that the meeting had been planned for months and sought to push back against the idea that it would aggravate tensions on the peninsula.

"It is not factually accurate to say that the event was conducted hastily. This has been many months in the planning," said Under Secretary of State Steve Goldstein, responding to the Russian foreign ministry's statement.

"We believe that this is another step forward in ensuring that the sanctions hold tight," he added, saying Washington would brief China and Russia.

"We all share the same view that it is time for North Korea to come to the table and let's negotiate a complete denuclearisation of the Korean Peninsula."

The two Koreas have agreed during rare talks to form a combined women's ice hockey team to take part in next month's Winter Olympics in the South.

The team will march together under a unified peninsula flag at the opening ceremony, a joint statement released by Seoul's unification ministry said.

North Korea will send a 550-member delegation, including 230 cheerleaders, 140 artists and 30 Taekwondo players for a demonstration, the ministry said.

The delegation is scheduled to begin arriving in South Korea on 25 January.

A North Korean delegation will visit the South next week to review the facilities at the games venue, Yonhap news agency reported.

South Korea also agreed to send its athletes to the North's Masikryong ski resort for training ahead of the Pyeongchang Olympics that run through 5-25 February.

North Korea's Olympic delegation will travel by land through Kaesong, which lies on the main road from Pyongyang to Seoul.

Seoul has long sought to proclaim the event a "peace Olympics" in the face of tension over the North's weapons programmes, which have seen it subjected to multiple UN Security Council sanctions, and the discussions represent a marked improvement.

Three officials from each side took part and the results will be discussed by both Koreas with the International Olympic Committee in Lausanne, Switzerland on Saturday.

The IOC must approve extra Olympic slots for the North's athletes after they failed to qualify or missed deadlines to register.