KIEV: Brawls erupted between rival factions on Ukraine's volatile Crimean peninsula Wednesday as the former Soviet nation's new leaders prepared to unveil a unity cabinet and Russian President Vladimir Putin ordered snap military drills near the border.

The untested pro-Western interim team in Kiev is grappling with the dual threats of separatism and default as it tries to recover from three months of protests that triggered pro-Russian president Viktor Yanukovych's ouster following a week of carnage in which nearly 100 people died.

A wave of secessionist sentiment that gripped the southeastern parts of Ukraine following the fall of the pro-Kremlin regime boiled over in Crimea as an angry crowd of a few thousand led by pro-Russian Cossacks squared off against a force of a similar size spearheaded by Muslim Tatars.

Local health authorities said one man died of a heart attack during the mayhem in the port town of Simferopol.

Ambulances were also called to treat several people who suffered head injuries during scuffles that involved pepper spray and saw several bottles being hurled.

Tensions were ratcheted up still further when Putin ordered the military to undergo snap readiness drills, one of several announced in recent months, across a western swathe of Russia that borders the northeast corner of Ukraine.

“The commander-in-chief has set the task of checking the capability of the armed forces to deal with crisis situations posing a threat to the military security of the country,” Defence Minister Sergei Shoigu said.

He also announced Russia was taking measures to ensure the security of its Black Sea naval fleet based in Crimea, a peninsula that had answered to Moscow for centuries until being handed to the Ukrainian Soviet republic as a gift in 1954.

Russia has been venting daily outrage at the meteoric turn of events in a neighbour that Putin views as vital to his dream of building a post-Soviet alliance that could rival the EU and Nato blocs.

Both US Secretary of State John Kerry and British Foreign Secretary William Hague gave the new leaders crucial backing on Tuesday and rejected Moscow's claim that Ukraine was being forced to make a choice between East and West.

Kerry attempted to ward off any ambitions Putin may have to use force to alter the political outcome in Kiev by urging the Kremlin “to keep its word” over Ukraine's unity.

“We are making it clear that every country should respect the territorial integrity here, the sovereignty of Ukraine.

Russia said it will do that, and we think it is important Russia keeps its word,” Kerry stressed.

The interim team's headaches have been compounded by Moscow's decision to freeze a massive bailout package that Putin promised to Yanukovych as his reward for rejecting closer EU ties in a surprise November decision that sparked the mass protests.

Fears of a catastrophic default by Ukraine, which is seeking $35 billion in Western aid to keep functioning, saw the local currency sink to a record low against the dollar Wednesday.

Russia blamed for Crimea unrest

The prospect of pro-Russian regions breaking away saw interim leader Oleksandr Turchynov on Tuesday abruptly walk out of an emergency session of parliament to consult his security chiefs.

Top among the concerns is the threat of mob violence in Crimea. Crowds have already ousted the mayor of Sevastopol, home to the Kremlin's navies for the past 250 years, and appointed a Russian citizen in his place.

The deposed head of state, wanted for “mass murder” and facing life behind bars, is widely believed to have gone into hiding in Crimea with his two sons and a small team of heavily-armed guards.

Ukraine interim prosecutor general insisted Yanukovych was still in the country while at the same time requesting an international arrest warrant both for the fugitive ex-leader and ousted interior minister Vitaliy Zakharchenko, a hate figure among protesters for ordering the deadly use of force.

Kiev's new leaders were offered some short-term relief when the Crimean parliament speaker cancelled a planned vote on the peninsula's secession.

But Wednesday's scuffles threatened to continue across the peninsula and spread to other pro-Russian regions such as Yanukovych's native industrial base of Donetsk.

Three of Ukraine's post-Soviet leaders, who included former Moscow ally Leonid Kuchma, issued a joint statement accusing Russia of “resorting to direct intervention in the political life of Crimea”.

Russia must “show respect to the choices made by the Ukrainian people and the Ukrainian government,” said a statement posted by former president Viktor Yushchenko and also featuring the names of Kuchma and former leader Leonid Kravchuk.