Ukraine's new government and most of the international community except Russia have said they will not recognize a result expected to be overwhelmingly in favor of immediate secession.

"This is a historic moment, everyone will live happily," Sergiy Aksyonov, the local pro-Moscow prime minister, told reporters after casting his ballot in the regional capital Simferopol.

"We will celebrate this evening," Aksyonov said.

Some 1.5 million people are called to vote on the Black Sea peninsula, which is mostly inhabited by ethnic Russians and has been controlled by Russian security troops over the past month.

Ukraine's interim President Oleksandr Turchynov called on Crimeans to boycott the ballot, accusing Russia of engineering it as part of an invasion plan.

"The result has been pre-planned by the Kremlin as a formal justification to send in its troops and start a war that will destroy people's lives and the economic prospects for Crimea," he said.

Crimea says foreign observers are monitoring the vote but the Organization for Security and Co-operation in Europe (OSCE) is not because it needs to be invited by a member state.

Voters can choose to become part of Russia or retain more autonomy but stay in Ukraine -- a vote for the status quo is not an option.

Preliminary results were expected soon after polls close at 8:00pm (1800 GMT) and Russian flags were already being handed out in the streets in Sevastopol.

Preparations to become part of the Russian Federation -- a process that could take months -- are to begin this week if the people vote for Moscow.

NJF/NJF