The Crimean parliament has voted to join Russia and will put the case to voters in a referendum on 16 March. Crimeans will be asked to vote whether the republic should join Russia or remain part of Ukraine.
Crimea's first deputy premier Rustam Temirgaliev announced the referendum, Itar-Tass news agency said.
Seventy-eight MPsin favour of the voted in favour of the referendum. There were eight abstentions.
Ukraine's interim economy minister condemned the referendum as unconstitutional.
"This is our response to the disorder and lawlessness in Kiev," Crimean MP Sergey Shuvainikov said.
"We will decide our future ourselves."
Sevastopol, which is not officially part of Crimea because of its special status, will be afforded a vote in the referendum.
"We will give Sevastopol an opportunity to have its say," said Shuvainikov.
Crimea is at the centre of a dangerous power struggle between Ukraine and Russia. More than 11,000 Russian forces occupy the Black Sea peninsula where Russia's only warm-water naval base is stationed.
The Crimean parliament asked the Russian government to "launch the procedure of Crimea becoming part of Russia".
When the decision was announced to thousands of people waiting outside the Crimean parliament building, they erupted with chants of "Russia!"
The region, which holds a majority ethnic Russian population, was strongly in favour of Ukrainian president Viktor Yanukovich prior to his ousting by anti-government protesters.