KIEV (AFP) - Ukraine's new Western-backed prime minister said on Tuesday 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 neighbour 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.

Ukraine's new premier - in power since the February 22 ouster of Moscow-backed president Viktor Yanukovych - is due to sign in Brussels on Friday the political portion of a landmark EU pact whose rejection by Yanukovych in November sparked the protests that led to his fall.

Yatsenyuk said he had decided to postpone signing the economic portion of the EU Association Agreement because he feared that its tough free-trade terms would negatively affect the factories dotting Ukraine's industrial southeast.

"For now, we have delayed signing the economic section of this document, taking into account the worries and fears... of the industrial regions, and especially those in the east," he said.

Yatsenyuk's address to the nation was meant to ease tensions between Ukrainian nationalists who spearheaded three months of protests against Yanukovych's regime in Kiev and Russian speakers who view the new pro-European government with mistrust.

But he began by saying that he had proof of Kremlin attempts to foment violence between the Russian and Ukrainian-speaking communities in the east that would then be used as an excuse to move in troops.

Putin has reserved the right to use force in Ukraine to "protect" ethnic Russians across the vast country.

"Unfortunately, Crimea is not the only region of indivisible Ukraine where foreign forces are trying to destabilise the situation, foment artificial conflicts, organise disturbances and provoke an armed aggression under the pretext of a so-called defence of Russian speakers," Yatsenyuk said.

He said Ukraine's police had "conclusive proof" that Russia's security services had sent agents into eastern cities such as Donetsk and Kharkiv, which saw three deaths in the past week in clashes between pro- and anti-Moscow demonstrators.

But Yatsenyuk also conceded there were ethnic Russians "who sincerely attend" pro-Kremlin protests and stressed that "we hear and listen to them, especially since they are knocking at an open door."