On Thursday, acting President Oleksander Turchinov issued the warning in the national parliament after armed men seized the regional government and parliament buildings in Crimea, where some ethnic Russians want the region to join the Russian Federation.

Ukraine puts its police on high alert after dozens of armed pro-Russia men stormed and seized local government buildings in Ukraine's Crimea region early Thursday and raised a Russian flag over a barricade, AP reported.

Up to 50 men with weapons marched into the buildings in the regional capital of Simferopol in a dawn raid and blocked government workers from entering, Crimean Prime Minister Anatoliy Mohilyov told AFP.

Meanwhile, fighter jets along Russia's western borders have been put on combat alert, the Russian Defense Ministry reported.

"Constant air patrols are being carried out by fighter jets in the border regions," Interfax quoted a ministry statement as saying on Thursday. "From the moment they received the signal to be on high alert, the air force in the western military region left for the ... air bases."

The renewed tension in this strategic peninsula that houses Russia's Black Sea fleet came as lawmakers in Kiev were expected to approve the new government, but also a day after clashes between pro- and anti-Russian demonstrators in Crimea's regional capital, Simferopol.

On Saturday, Ukraine parliament voted to remove pro-Russia President Viktor Yanukovych from power only hours after his escape from Kiev to the northeastern city of Kharkov, while jailed former prime minister Yulia Tymoshenko were released.

NTJ/NJF