Russia has vetoed a UN Security Council draft resolution that declared a planned referendum on the status of Ukraine's Crimea region "can have no validity" and urged nations and international organizations not to recognize it.
The Russian veto of the draft resolution, drawn up by the United States, was expected.
Moscow, which has sent military forces to the Crimea, is backing Sunday's referendum, which would transfer control of the region from Ukraine to Russia.
The brief resolution noted that the referendum was not backed by the Ukrainian government in Kiev.
"This referendum can have no validity, and cannot form the basis for any alteration of the status of Crimea," it states. It calls on "all states, international organizations and specialized agencies not to recognize any alteration of the status of Crimea on the basis of this referendum."
France's President Hollande has said sanctions on military cooperation with Russia would be part of the next level of steps over the Ukraine crisis.
On Monday the US and European Union are expected to unveil a list of Russian officials subject to asset freezes and visa bans as Western nations attempt to step up pressure on Moscow over its intervention in the Ukrainian region of Crimea.
When asked whether France would suspend a 1.2 billion euro helicopter carrier contract with Russia, Hollande told a news conference: "As far as other sanctions, notably military cooperation, that is the third level of sanctions."
Vladimir Putin is currently meeting the head of Ukraine's Paralympic committee, according to the Kremlin.
A spokesman said that Valeriy Sushkevich also met Putin before the start of the Games earlier this month.
Ukraine decided to take part despite the Crimea crisis, but threatened to pull out in the event of an escalation of violence.
Foreign Secretary William Hague has called for a "firm and united" response from the European Union after diplomatic crisis talks on Ukraine failed to achieve a breakthrough.
Mr Hague said EU foreign ministers should press ahead with sanctions against Moscow after the Russians made clear they would back a referendum by Crimea to break away from Ukraine and join Russia.
Mr Hague last night described the failure of the talks as "deeply disappointing" and condemned Russia's decision to support Sunday's "illegal, unconstitutional and illegitimate" referendum - which is widely expected to deliver an overwhelming vote to break away from Ukraine.
"The door remains open for diplomacy and dialogue and we urge the Russian government to take action to lower tensions and enter into direct talks with the Ukrainian government", he said.
International observers invited by Russia and Crimean authorities have arrived in Simferopol ahead of Sunday's referendum.
The internationally condemned referendum in Crimea will go ahead as planned on Sunday with no doubt among the organisers that the Ukrainian region will vote to join Russia, ITV News Europe Editor James Mates has said.
Watch his latest report from the regional capital Simferopol:
The United States stands ready to "respond quickly" if a referendum on Crimea's defection to the Russian Federation is held as planned on Sunday, the White House has said.
Washington said it was "regrettable" that Russia had chosen not to act to reduce tensions in the Ukrainian region after US Secretary of State John Kerry held talks with Sergei Lavrov.
Mr Kerry has meanwhile tweeted a photo of his discussion with the Russian Foreign Minister, saying "many ideas" had been "put forward" during the six-hour talks.
NATO's Secretary-General has condemned the planned referendum in Ukrainian's Crimea region, saying it would break international law and have no "political legitimacy".
The statement was issued after a meeting of ambassadors from 50 nations, including Russia and Ukraine, ahead of Sunday's vote in Crimea.
– NATO Secretary-General Anders Fogh Rasmussen
The so-called referendum in the Ukrainian Autonomous Republic of Crimea planned on 16 March would be a direct violation of the Ukrainian constitution and international law.
If held, it would have no legal effect or political legitimacy.
Holding this referendum would undermine international efforts to find a peaceful and political solution to the crisis in Ukraine.
US Secretary of State John Kerry has warned Russia that ratifying a Crimea referendum result in the Russian parliament will amount to a "back-door annexation" of the Ukrainian region.
Mr Kerry said the international calls for sanctions as "a response" to the "illegal" referendum being held were not a threat to Russia but a necessary step to "respecting the integrity of Ukraine".
"It is not our preference," he said, but a "justified" step due to the "breach of international law".
He added, though, that the international community still "does not know definitively" what Vladimir Putin will decide about Russia's response to a referendum on Crimea and insisted the US had put "plenty of options on the table" for the Russian President to take a different course.