KIEV (AFP) - Militant anti-government activists in Ukraine on Saturday threatened to storm the president's palace and shatter a fragile peace deal to end the ex-Soviet country's bloodiest crisis since independence.

Embattled President Viktor Yanukovych signed a deal on Friday with the opposition paving the way for early elections and forming a unity government while granting amnesty for protesters detained during three days of unrest that claimed nearly 100 lives.

But the agreement was met with scepticism by many of the Ukrainians who have occupied Kiev's central Independence Square since November, when Mr Yanukovych sparked outrage by ditching a deal for closer EU integration in favour of stronger ties with old master Russia.

"Elections in December are not enough - he has to leave now," said 34-year-old Oleh Bukoyenko as he joined 40,000 protesters to hear the peace pact's details announced on the square late on Friday.

Up to 10,000 people remained on the charred square on Saturday morning despite the agreement, demanding that the president step down after a week of bloodshed saw riot police use live rounds against anti-government protesters.

The crisis in Kiev has evolved into a Cold War-style standoff between Moscow and the West over the future of the strategic nation sandwiched between them.

Russia - which has promised a US$15-billion (S$19 billion) bailout to its economically struggling former satellite following Mr Yanukovych's decision to drop the EU deal - has also expressed reservations about Friday's agreement.