Mikhail Malyshev, Crimea's election commission chairman, said Thursday 50 politicians and observers have been registered to attend the referendum, widely seen as laying the groundwork for the autonomous, pro-Moscow region to be annexed by Russia, RIA Novosti reported Friday.
On Sunday, residents in the majority Russian-speaking Crimea will be given two options -- joining Russia or remaining in Ukraine with expanded autonomy, RIA Novosti said. A "no" option is not on the ballot.
Malyshev said preliminary results will be released Monday.
The United States and other countries have called the referendum illegal and said they would not recognize the results. The international community also condemned Russia's attempt to annex the region.
The Crimea Parliament declared independence from Ukraine Tuesday, adding in its statement that if the popular vote is approved, Crimea will become independent and immediately request annexation by Russia.
Officials in Crimea, which is home port for Russia's Black Sea fleet, have refused to recognize the country's new leadership in Kiev as legitimate following the ouster of President Viktor Yanukovych in late February after months of demonstrations protesting his decision not to sign political and trade agreements with the European Union in favor of closer ties with Russia.