US will never accept Crimean referendum: Obama tells Putin

The United States and international community will never recognise the Crimean referendum to secede from Ukraine, US President Barack Obama has told Russian counterpart Vladimir Putin.

During a telephonic call with Putin yesterday, after the people of Crimea - a province of Ukraine - overwhelmingly voted to merge with Russia, Obama said the Crimean "referendum," not only violated the Ukrainian constitution, but also occurred under duress of Russian military intervention.

"He emphasised that Russia's actions were in violation of Ukraine's sovereignty and territorial integrity and that, in coordination with our European partners, we are prepared to impose additional costs on Russia for its actions," the White House Press Secretary Jay Carney said.

Obama underscored that there remains a clear path for resolving this crisis diplomatically, in a way that addresses the interests of both Russia and the people of Ukraine, he said.

The US President noted that the Ukrainian government continues to take concrete steps that would allow for the de-escalation of the crisis, particularly as it prepares for elections this Spring and undertakes constitutional reform.

He asked Russia to support the immediate deployment of international monitors to help prevent acts of violence by any groups.

According to the White House, Obama reiterated that a diplomatic resolution cannot be achieved while Russian military forces continue their incursions into Ukrainian territory and that the large-scale Russian military exercises on Ukraine's borders are only exacerbating the tension.

Obama said that the Secretary of State, John Kerry, continues to be ready to work together with the Russian Foreign Minister, Sergei Lavrov, and the Ukrainian government to find a diplomatic resolution to the crisis.

Earlier Carney rejected the "referendum" in the Crimean region of Ukraine.

"No decisions should be made about the future of Ukraine without the Ukrainian government. Moreover, this vote was not necessary.

"The Ukrainian government has made clear its willingness to discuss increased autonomy for Crimea, and the presidential elections planned for May 25 provide a legitimate opportunity for all Ukrainians to make their voices heard on the future of their country," Carney said.

In addition, Ukraine, the United States, the EU, the OSCE, the UN, and others have called for Russia to allow international monitors into the Crimean peninsula to ensure that the rights of ethnic Russians in Ukraine are being upheld, he said.

"Russia has spurned those calls as well as outreach from the Ukrainian government and instead has escalated its military intervention into Crimea and initiated threatening military exercises on Ukraine's eastern border," he added.

Describing the Russian actions as dangerous and destabilising, Carney said the UN Security Council recognised this in a vote yesterday that only Russia opposed.

"As the United States and our allies have made clear, military intervention and violation of international law will bring increasing costs for Russia - not only due to measures imposed by the United States and our allies but also as a direct result of Russia's own destabilising actions," he said.