Russia Accused Of 'Armed Invasion' In Ukraine

Russia has been accused of an "armed invasion" after dramatically increasing its military presence in Ukraine's Crimean peninsula.

The country's Acting President, Oleksandr Turchynov, urged Russian President Vladimir Putin to stop "provocations" and "naked aggression", and pull back military forces.

Ukrainian security sources said they had regained control of Simferopol and Sevastopol airports amid claims Russian forces tried to seize them.

US President Barack Obama will deliver a statement on the crisis shortly.

As the crisis took a new turn, the ousted President, Viktor Yanukovych, vowed to fight on, claiming he had been forced out by a minority of "pro-fascist thugs" after protests against his decision to reject a European Union trade deal.

British Foreign Secretary William Hague will visit the country on Sunday and hold talks with Ukraine's new leaders. High on the agenda will be the increased tensions in Crimea.

Armed men were seen patrolling the perimeter at Simferopol, a civilian airport, and there were also reports Russian forces were blocking Sevastopol's military airport.

Despite the claims from Kiev, a military source quoted by the Interfax news agency said the armed men at Sevastopol had extended their control by taking over the runway.

Ukraine's State Border Guard Service said about 30 Russian marines from the country's Black Sea Fleet had taken up position outside the coast guard base in Sevastopol.

More than 10 Russian military helicopters were also seen flying from the country into Ukrainian airspace over the Crimea region earlier on Friday.

Interior minister Arsen Avakov accused Moscow of staging an "armed invasion" in Crimea, a charge Russia firmly denies.

However, Moscow has said armoured vehicles were moving around Crimea for "security reasons".

Sky News Senior Correspondent Alex Rossi, who is in Crimea, said the new government in Kiev is seen as a threat by Russia.

"Ukraine has always been viewed by the Russian ruling elite as part of its sphere of influence," he said.

"Moscow may have lost the Western part of Ukraine (for now?) but you can bet it will not allow the same thing to happen in the south and the eastern parts of the country."

Mr Putin adopted a conciliatory tone in a call with a number of world leaders, saying there must be no further escalation in the crisis.

He spoke with Prime Minister David Cameron, German Chancellor Angela Merkel and European Union President Herman van Rompuy.

A Downing Street spokesperson said Mr Cameron emphasised that all countries should respect the territorial sovereignty of Ukraine and the pair agreed free and fair elections were the best way to "secure a positive future" for the country.

The Foreign Office is advising against all visits to the Crimean peninsula and has called on those already there to leave.

US Secretary of State John Kerry also discussed the tensions in the region in a phone call with Russia's Foreign Minister Sergei Lavrov.

Mr Kerry said Washington is watching to see if Russian movement "might be crossing a line in any way" and urged Moscow not to do anything to inflame the situation.

The United Nations Security Council will hold an emergency private meeting on Friday about Ukraine. Spokesman Martin Nesirky said the UN was "obviously concerned" and called on all sides to reduce tensions.

Speaking at a televised press conference in the Russian city of Rostov-on-Don, Mr Yanukovych said he would return to govern the country once he receives "international safety guarantees".

But Kiev has begun the process of extraditing the ousted leader from Russia on charges of mass murder after clashes between protesters and police left more than 80 people dead.

Mr Yanukovych blamed the "irresponsible policies" of the West for the crisis and apologised "to the Ukrainian people" for not having had more strength.

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