Russia's Interfax news agency reported on Saturday that the country's lower house of parliament, the Duma, had called on President Putin to use all possible means to stabilize the situation in the Crimea.

"The Duma Council adopted an appeal to the president of Russia, in which parliamentarians are calling on the president to take measures to stabilize the situation in Crimea and use all available means to protect the people of Crimea from tyranny and violence," Interfax quoted speaker Sergei Naryshkin as saying.

This came just hours after an appeal from Crimea's Prime Minister Sergei Aksyonov, who was elected to office by lawmakers just last Thursday.

"Understanding my responsibility for the life and security of citizens, I appeal to the president of Russia, Vladimir Putin, for assistance in guaranteeing peace and calmness on the territory of the autonomous republic of Crimea," he said in a statement.

European appeals

Saturday's developments have been met with urgent appeals from European Union countries to refrain from any acts that would spark a military conflict.

German Foreign Minister Frank-Walter Steinmeier released a statement in which he called on the Kremlin to respect Ukraine's sovereign territory.

"Everything that Russia does must be in keeping with the sovereignty and territorial integrity of Ukraine," Steinmeier said.

"France is extremely concerned by the reports from Crimea, which describe significant troop movements," French Foreign Minister Laurent Fabius said in a statement. "We call on the parties to abstain from acts that could raise tensions and affect Ukraine's territorial unity."

British Foreign Secretary William Hague used his Twitter account to deliver a similar statement.

"Have spoken to (Russian) Foreign Minister (Sergei) Lavrov to call for de-escalation in Crimea and respect for sovereignty and independence of Ukraine," he tweeted.

On Friday, US President Barack Obama also warned Russia against intervening in Crimea.

Rapidly developing situation on the ground

Also on Saturday, Aksyonov told the Interfax news agency that the troops in question guarding key buildings in Crimea's main city, Simferopol, were members of Russia's Black Sea Fleet.

Meanwhile, the city's international airport remained closed on Saturday.

"Due to limitations in the use of the airspace, the airport has temporarily suspended receiving flights," the airport said in a statement.

Armed men had seized control of the airport on Friday. Ukrainian military sources say that Russian servicemen also controlled military airports in Belbek near Sevastopol and in Kirovskoye in the east of Crimea.

pfd/tj (Reuters, AFP, dpa, AP)