The Ukrainian party of former boxer turned politician Vitali Klitschko urged Kiev on Tuesday to cut diplomatic ties with Moscow, as Russia moved to admit Crimea into its territory.

"Given the Russian authorities' hostile acts and international practice, we insist that diplomatic relations between Ukraine and Russia be immediately cut," the UDAR party said in a statement, as Russian President Vladimir Putin prepared to sign a treaty making Crimea part of Russia.

Also on Tuesday,  Ukraine's new Western-backed prime minister said that the ex-Soviet country had no plans to join NATO following last month's fall of a pro-Kremlin regime.

"For the sole purpose of preserving the unity of Ukraine, the issue of (Ukraine's) accession to NATO is not on the agenda," Arseniy Yatsenyuk said in a televised address delivered in Russian and intended specifically for the southeastern parts of his nation of 46 million.

"The country will be defended by a strong and modern Ukrainian army," he said.

Ukraine signed up to a partnership deal with NATO in 1997 after the fall of communism and the end of the Soviet Union but it is not a full member of the military alliance.

In his speech, Yatsenyuk accused Moscow of taking aim at Ukraine's volatile Russian-speaking southeastern regions after pressing ahead with widely condemned plans to absorb the flashpoint Black Sea peninsula of Crimea, heightening tensions in the biggest East-West standoff since the Cold War.

Moscow this week unveiled its own plan for settling the Ukrainian crisis that included a provision for its neighbor to assume "a neutral political and military status" whose sovereignty would be guaranteed by Russia as well as the European Union and the United States.