Dozens of armed men in military uniforms have reportedly seized an airport in Ukraine's strategic Crimea region.

Witnesses told the Interfax news agency that the 50 or so men, seen early Friday, were wearing the same gear as those who seized government buildings in the regional capital of Simferopol on Thursday and raised the Russian flag.

The report says the men with "Russian navy ensigns" surrounded the Simferopol Airport's domestic flights terminal.

The report could not be immediately confirmed. It comes one day after masked gunmen stormed Crimea's parliament building

The events in the region have heightened tensions with neighbouring Russia, which on Thursday scrambled fighter jets to patrol borders while Ukraine's newly formed government pledged to prevent a national breakup with the strong backing of the West.

Moscow reportedly granted shelter to Ukraine's fugitive president, Viktor Yanukovych, who was said to be holed up in a luxury government retreat and to have scheduled a news conference Friday near the Ukrainian border. As gunmen wearing unmarked camouflage uniforms erected a sign reading "Crimea is Russia" in the provincial capital, Ukraine's interim prime minister declared that the Black Sea territory "has been and will be a part of Ukraine."

The escalating conflict sent Ukraine's finances plummeting further, prompting Western leaders to prepare an emergency financial package.

Yanukovych, whose approach to Moscow set off three months of pro-Europe protests, finally fled by helicopter last weekend as his allies deserted him. The humiliating exit was a severe blow to Russian President Vladimir Putin, who had been celebrating his signature Olympics even as Ukraine's drama came to a head. The Russian leader has long dreamt of pulling Ukraine — a huge country of 46 million people considered the cradle of Russian civilization — closer into Moscow's orbit.

For Ukraine's neighbours, the spectre of Ukraine breaking up evoked memories of centuries of bloody conflict.

"Regional conflicts begin this way," said Polish Foreign Minister Radoslaw Sikorski, calling the confrontation "a very dangerous game."

Russia has pledged to respect Ukraine's territorial integrity. But the dispatch of Russian fighter jets Thursday to patrol borders and drills by some 150,000 Russian soldiers — almost the entirety of its troop force in the western part of the country — signalled strong determination not to lose Ukraine to the West.

Thursday's dramatic developments pose an immediate challenge to Ukraine's new authorities as they named an interim government for the country, whose population is divided in loyalties between Russia and the West. Crimea, which was seized by Russian forces in the 18th century under Catherine the Great, was once the crown jewel in Russian and then Soviet empires.

Russian flag raised

In the capital, Kyiv, the new prime minister said Ukraine's future lies in the European Union, but with friendly relations with Russia.

Arseniy Yatsenyuk, picked Thursday in a boisterous parliamentary session, now faces the thorny task of restoring stability in a country that is not only deeply divided politically but on the verge of financial collapse.

They didn't look like volunteers or amateurs; they were professionals. - Witness to seizure of government buildings

Shortly before the lawmakers chose him, Yatsenyuk insisted that the country wouldn't accept the secession of Crimea. The Black Sea territory, he declared, "has been and will be a part of Ukraine."

In Simferopol, the Crimean regional capital, gunmen toting rocket-propelled grenades and sniper rifles raised the Russian flag over the local parliament building. The men threw a flash grenade in response to a journalist's questions. They wore black and orange ribbons, a Russian symbol of victory in the Second World War.

Maxim, a pro-Russian activist who refused to give his last name, said he and other activists had camped overnight outside the local parliament when between 50 and 60 men took over the building.

A pro-Russian demonstrator waves Russian and Crimean flags from an old Soviet army tank during a protest in Simferopol, Ukraine, where armed men seized government buildings Thursday and raised the Russian flag. (Darko Vojinovic/Associated Press) ​"They were asking who we were. When we said we stand for the Russian language and Russia, they said: `Don't be afraid. We're with you.' Then they began to storm the building bringing down the doors," he said. "They didn't look like volunteers or amateurs; they were professionals. This was clearly a well-organized operation."

"Who are they?" he added. "Nobody knows."

CBC correspondent Susan Ormiston said many people gathered on Thursday were happy about the takeover.

"They are grouped around here today again showing their support for closer ties to Russia and away from the new government in Kyiv," she said.

Oleksandr Turchynov, who stepped in as acting president after Yanukovych's flight, condemned the assault as a "crime against the government of Ukraine." He warned that any move by Russian troops off of their base in Crimea "will be considered a military aggression."

"I have given orders to the military to use all methods necessary to protect the citizens, punish the criminals, and to free the buildings," he said.

Baird arrives in Kyiv

In a bid to shore up Ukraine's fledgling administration, the Washington-based International Monetary Fund says it is "ready to respond" to Ukraine's bid for financial assistance. The European Union is also considering emergency loans for a country that is the chief conduit of Russian natural gas to Western Europe.

Russia still sees Viktor Yanukovich as the legitimate president of Ukraine. (Konstantin Chernichkin/Reuters) ​IMF chief Christine Lagarde said in the organization's first official statement on Ukraine's crisis that it is intense talks with its partners on "how best to help Ukraine at this critical moment in its history." Ukraine's Finance Ministry has said it needs $35 billion for this year and next to avoid default. Ukraine's currency, the hryvnia, dropped to a record low of 11.25 to the U.S. dollar, a sign of the country's financial distress.

Western leaders lined up to support the new Ukrainian leadership, with the German and British leaders warning Russia not to interfere.

"Every country should respect the territorial integrity and sovereignty of the Ukraine," British Prime Minister David Cameron said after a meeting with German Chancellor Angela Merkel in London.

Foreign Affairs Minister John Baird said via Twitter that Ottawa welcomes the “new, legitimate” government in Kyiv, calling its formation a “vital step forward” to restoring democracy.

Baird arrived in Ukraine earlier today, leading a delegation of Tory parliamentarians and Ukrainian-Canadians.

Yet the prospect of the West luring Ukraine into NATO is the very nightmare that Russia is desperately trying to avoid. Trenin of the Carnegie Center said a Ukraine-NATO courtship "would really raise the alarm levels in Moscow."

Reports place Yanukovych near Moscow

Yanukovych declared Thursday in a statement that he remains Ukraine's legitimate president. He was reportedly to hold a news conference Friday in the southern Russian city of Rostov-on-Don, not far from the Ukrainian border.

A respected Russian news organization said that the fugitive leader was staying at the Kremlin-run Barvikha retreat just outside Moscow, though spokesmen for Putin and for the department that runs the resort told The Associated Press that they had no information about Yanukovych's whereabouts.

Yanukovych fled after riot police attacked protesters in Kiev's central square in clashes that killed more than 80 people, and European and Russian officials intervened. He has not been seen publicly since Saturday.

On Thursday, the White House said Yanukovych "abdicated his responsibility" and welcomed the Ukrainian parliament's efforts to stabilize the country.

The Russian Foreign Ministry voiced concern about the Russian-speaking population in Ukraine and vowed to protect their interests. Putin on Thursday asked the government to consider providing humanitarian assistance to Crimea.

State-owned ITAR-Tass news agency quoted a statement read at a session of the ministry's board on Thursday, saying that Russia "will have a firm and uncompromising response to violations of the rights of compatriots by foreign states."