(NBC News) -- More than 96 percent of Crimeans who voted in the region's disputed referendum backed breaking away from Ukraine and joining Russia, an official said Monday.
The United States and European Union said Sunday's vote was illegal, carried out with the backing of Moscow and with the presence of armed pro-Russian forces on the Ukraine's southern peninsula.
Mikhail Malyshe, head of the referendum commission, said in a televised news conference Monday that the final tally was 96.8 percent in favor of splitting from Ukraine, according to The Associated Press.
The referendum gave people two options: break away from Ukraine and join Russia, or return to its 1992 constitution, which gave it powers to decide how much freedom it had from Kiev. Some analysts said this would be a step toward independence, and with it tacit control from Moscow.
Crimea's Muslim minority Tatars and some Ukrainians said they would boycott the ballot. The turnout was 83 percent, according to election officials.
Crimea's parliament was set to meet Monday to formally request to be annexed by Russia. The U.S. and E.U. foreign ministers said they are considering more sanctions on Russia over its actions in Crimea.
The recently formed administration in Kiev called the referendum a "circus" directed at gunpoint by Moscow, the AP reported on Monday.
The referendum in largely Russian-speaking Crimea followed an uprising in Kiev last month, after which to President Viktor Yanukovych gave up many of his powers to parliament and traveled to Russia.
The new Kiev administration was met in Crimea with pro-Russian protests. And so-called pro-Russia "self defense forces" - assumed by many to be Russian troops minus their markings - took control of strategic positions.
The Associated Press contributed to this report.