The speaker of Russia's upper house of parliament says Russian lawmakers will support Crimea's decision if the Ukrainian region decides in a referendum to join Russia.
Meanwhile, Ukraine's interim president, Oleksandr Turchynov, signed a decree Friday canceling the decision by Crimea's parliament to hold the referendum. The Moscow-backed regional legislature voted Thursday for the peninsula to become part of Russia and scheduled a referendum on the issue for March 16.
Mr. Turchynov on Thursday called the decision to hold a referendum a "farce" and accused the Russian military of organizing the vote. He said he and the Ukrainian parliament would protect the country's integrity and sovereignty.
Ukraine's interim prime minister said Friday that "no one in the civilized world" will recognize the referendum's results.
Arseniy Yatsenyuk told reporters he wants to "warn separatists" and others he described as "traitors of the Ukrainian state" that their decisions are "unlawful" and "unconstitutional." U.S. and European leaders have also called the referendum illegal.
Ukraine and Russia have been locked in a tense standoff since Russian forces entered the Crimean peninsula a week ago.
The Reuters news agency Friday quoted an official in Ukraine's border guard service as saying that Russia now has 30,000 troops in Crimea, nearly double the figure previously given by Ukrainian authorities.
U.S. President Barack Obama spoke by phone Thursday with Russian President Vladimir Putin about the Ukraine crisis, but the two leaders found little common ground.
The White House says Mr. Obama told Mr. Putin the presence of Russian forces in Crimea is a violation of Ukraine's sovereignty. The Kremlin says Mr. Putin denounced Ukraine's new government as "illegitimate" and said Russia cannot "ignore" calls for help from Ukraine's Russia-leaning east and south.
Earlier Thursday, Mr. Obama authorized sanctions, including visa restrictions, against those found to have violated Ukraine's territorial integrity. The EU also took measures against Russia, suspending talks on visas and a new economic agreement.
Russia's Foreign Ministry on Friday called the EU's position "extremely unconstructive," adding that Russia "will not accept the language of sanctions and threats" and promising retaliation if the EU imposes sanctions.
Ukrainian Prime Minister Yatsenyuk said Friday his government is "prepared to rebuild relations with Russia." But he said Russia must withdraw its troops, fulfill its agreements with Ukraine and stop supporting separatists in Crimea.
The White House says Mr. Obama, in his phone conversation with Mr. Putin, called for direct talks between Kyiv and Moscow that would be mediated by the international community. Mr. Obama called for all Russian forces to return to their bases and for international monitors to ensure the safety of Ukrainians, including ethnic Russians.
On Capitol Hill, the U.S. House of Representatives voted to provide loan guarantees of $1 billion to Ukraine. That measure now goes to the U.S. Senate. The European Union is prepared to extend a $15 billion bailout to Kyiv if Ukraine can reach an agreement with the International Monetary Fund.
Ukraine's crisis began when protests erupted in late November after then-President Viktor Yanukovych rejected an economic deal with the EU in favor of closer ties with Russia. What began as peaceful protests quickly turned violent, leading to the deaths of more than 80 protesters and charges that the Yanukovych government ordered snipers to shoot protesters. Mr. Yanukovych fled Ukraine last month.