Ukraine's interim premier on Thursday warned the Security Council that nuclear non-proliferation could be undermined by the Crimea crisis, but insisted that a peaceful solution was not out of reach.

One day after winning full support from US President Barack Obama in Washington, Arseniy Yatsenyuk delivered a short address in English and Russian at an emergency session of the Council.

"We still believe that we have a chance to resolve this conflict in a peaceful manner," the prime minister said.

"We urge the Russian Federation to pull back its military forces deployed in Crimea to barracks and to start real talks and negotiations in order to tackle this conflict," he added.

Ukraine in 1994 gave up its nuclear arsenal, the interim prime minister reminded the Council but global security would be at risk unless the crisis could be resolved properly.

Yatsenyuk said that, unless Russia agrees to a real dialogue, the crisis could undermine global security and nuclear non-proliferation.

"As after these actions it would be very difficult to convince anyone in the globe not to have nuclear weapons," he said.

"We want to have talks. We don't want to have any kind of military aggression," added the premier, before turning to address Russian ambassador Vitaly Churkin directly in Russian.

Britain and the United States expressed support for Ukraine and condemned a referendum planned Sunday in Crimea to decide whether the region should stay with Ukraine or join Russia.

US Secretary of State John Kerry would Friday meet his Russian counterpart, US ambassador Samantha Power told the Council.

"None of us can afford to leave any stone unturned, but Russia has to want a diplomatic solution," she said.

British ambassador Mark Lyall Grant said the Council was meeting in the "gravest possible circumstances".

Going ahead with Sunday's referendum, illegal under Ukrainian law, would be "inflammatory and destabilising," Grant said, adding it would have "serious implications for the UN charter".

"It would be dangerous and irresponsible for Russia to take unilateral actions or collude with unilateral actions of the Crimea authorities," Grant said.