The spiralling tensions in a nation torn between the West and Russia are set to take another dramatic turn when ousted president Viktor Yanukovych briefs reporters in Russia on Friday after winning protection from Moscow.
The head of Ukraine's security and defence council said Russian soldiers and local pro-Kremlin militia were responsible for the dawn raids on Crimea's main airport and another base on the southwest of the peninsula where pro-Moscow sentiment runs high.
A spokesman for Russia's Crimea-based Black Sea Fleet denied any involvement in the airport occupations. But Ukraine's parliament immediately appealed to the US and Britain to uphold a 1994 pact with Russia that guaranteed the country's sovereignty in return for it giving up its Soviet nuclear arms.
Both lawmakers and UN Security Council chair Lithuania said they would also ask the world body to address the Crimea crisis at its next session -- a request that would need to gain support from veto-wielding members such as Russia.
Interim president Oleksandr Turchynov meanwhile attempted to regain control over unravelling security in the vast nation of 46 million by sacking the armed forces chief appointed by Yanukovych at the height of deadly protests last week.
Western governments have been watching with increasing alarm as Kiev's new rulers grapple with the dual threats of economic collapse and secession by Russian-speaking southern and eastern regions that had backed Yanukovych.
Russian President Vladimir Putin this week stoked concerns that Moscow might use its military might to sway the outcome of Ukraine's three-month standoff by ordering snap combat drills near the border involving 150,000 troops and nearly 900 tanks.
US Secretary of State John Kerry attempted to relieve diplomatic pressure in a crisis that has increasingly assumed Cold War overtones by announcing that Russian Foreign Minister Sergei Lavrov had assured him Moscow "will respect the territorial integrity of Ukraine".
Putin also appeared to take a more conciliatory approach Thursday by vowing to work on improving trade ties and promising to support international efforts to provide Kiev with funds that could keep it from declaring a debt default as early as next week.
But tensions were soaring by the hour in Russian-speaking Crimea -- a scenic Black Sea peninsula that has housed Kremlin navies for nearly 250 years and was handed to Ukraine as a symbolic gift by a Soviet leader in 1954.
- 'Armed invasion' -
Ukraine's National Security and Defence Council chief Andriy Parubiy told reporters that security forces had successfully repelled "an attempt to seize the airports" by Russian soldiers and local pro-Kremlin militias.
"The airports are now controlled by Ukrainian law enforcement authorities," Parubiy said in televised remarks.
Dozens of men in battle fatigues and armed with Kalashnikovs had earlier encircled the Simferopol airport and were checking all incoming and outgoing traffic although flights continued on schedule.
AFP reporters also saw soldiers with machine guns and dressed in green military fatigues that carried no national identification blocking the main road leading to Ukraine's Belbek military air base near the city of Sevastopol -- home to Russia's Black Sea Fleet.
Interior Minister Arsen Avakov said he viewed the incident as "an armed invasion and an occupation" by Russia.
The peninsula of nearly two million people has been in crisis since dozens of pro-Kremlin gunmen seized Crimea's parliament and government buildings Thursday and raised the Russian flag.
Crimean lawmakers appointed Russian Unity party member Sergiy Aksyonov as regional premier in place of a Kiev ally in a vote held late Thursday under the watchful eye of the militiamen.
Aksyonov said Friday he still recognised Yanukovych as Ukraine's legitimate head of state.
- Yanukovych emerges in Russia -
The fugitive leader has not been seen since making a brief taped television appearance that aired Saturday only hours before parliament stripped him of power in the wake of a week of carnage in Kiev that claimed nearly 100 lives.
Ukraine's bloodiest crisis since its 1991 independence erupted in November when Yanukovych made the shock decision to ditch an EU trade pact in favour of closer ties with old master Russia, sparking mass anti-government protests.
The 63-year-old announced from an undisclosed location on Thursday that he still considered himself Ukraine's legal head of state and was "compelled to ask the Russian Federation to ensure (his) personal security."
Sources in his entourage said the deposed leader will appear before the media at 1300 GMT in Rostov-on-Don -- a Russian city less than two hours' drive from the Ukrainian border.
But Ukraine's general prosecutor said that Kiev would ask Moscow to extradite Yanukovych -- accused of "mass murder" over the protest deaths -- if his presence in Russia is confirmed.
Swiss bank accounts
Meanwhile Switzerland said it was freezing the assets of 20 Ukrainian figures, including Yanukovych and his multi-millionaire son Olexandr, and also launching a money laundering probe.
Austria announced a similar move against 20 Ukrainian figures but did not identify them.
It is unclear whether Yanukovych himself has any funds in Switzerland. But his 40-year-old son opened a branch of his Management Assets Company (MAKO) in Geneva in late 2011.
Switzerland said it wanted to "avoid any risk of misappropriation of Ukrainian state assets".
Ukraine's new leaders are suffering from Moscow's decision to freeze a $15-billion bailout package Putin promised to Yanukovych in return for his rejection of the EU deal.
The central bank was forced on Friday to lower the maximum amount of money individuals can withdraw from banks in a day to about 1,100 euros ($1,400) from a 4,000-euro ($5,500) limit imposed on February 7.
The hryvnia had plunged about 13 percent between Wednesday and Thursday before regaining some strength on Friday amid expectations of the imminent delivery of urgent Western aid.