KIEV, Feb. 28 (Xinhua) -- Ukrainian Interior Minister Arsen Avakov said Friday the seizure of two airports on the southern Crimea Peninsula was an "occupation and armed invasion" .
"It is a violation of all international treaties and norms. This is a direct provocation aimed at armed bloodshed in the territory of a sovereign state," Avakov wrote in a statement.
Earlier in the day, an armed group took control of the two airports of Crimea's capital Simferopol.
Some 50 armed men carrying Russian navy flags took control of the airports overnight after arriving in trucks, the Interfax news agency reported.
Witnesses were quoted as saying the armed men were wearing the same gear as those who seized local government buildings in Simferopol.
On Thursday, security forces in Crimea were put on alert after an armed group seized local government and parliament buildings.
The Crimean Peninsula is a Russian-speaking Ukrainian region, where many ethnic Russians and Crimean Tatars live. The region occasionally witnesses clashes between different ethnic groups.
Tensions escalated in the area this week following the dismissal of Kremlin-friendly President Viktor Yanukovych, who was reportedly to hold a news conference Friday in the southern Russian city of Rostov-on-Don, not far from the Ukrainian border.
Meanwhile, Parliament Speaker Alexandr Turchynov, who is also Ukraine's acting president, urged Russian naval troops to refrain from going beyond the base of the Black Sea Fleet on the Crimea Peninsula.
Any troop movements outside the base "will be considered as military aggression," he told parliament.
In April 2010, Ukraine renewed the lease of Russia's Black Sea Fleet on its Crimean Peninsula for 25 years in exchange for gas price discounts.