Mr Yushchenko, who is visiting Italy, announced Ukraine's third general election in less than three years on television, in a pre-recorded speech.

The coalition collapsed after Prime Minister Yulia Tymoshenko backed a move to reduce the president's powers.

In his speech, the president blamed its collapse on her "thirst for power".

Many analysts believe Ms Tymoshenko will stand for president in 2010.

She and Mr Yushchenko were allies during the 2004 "Orange Revolution" which swept pro-Western forces to power after a discredited presidential election.

'Ruined by ambition'

The president did not set a date for the new election.

"In conformity with the Ukrainian constitution, I halt the parliament's powers and announce parliamentary elections," he said in his five-minute speech.

"The vote will take place in democratic and lawful fashion."

"I am convinced, deeply convinced that the democratic coalition was ruined by one thing alone - human ambition," he continued.

"The ambition of one person. Thirst for power, different values, personal interests taking precedence over national interests."

Mr Yushchenko's Our Ukraine party pulled out of the coalition on 3 September after the Tymoshenko Bloc sided with the pro-Moscow opposition Party of Regions to pass several laws Mr Yushchenko saw as a threat to his presidential powers.

The coalition was officially dissolved on 16 September and parties had 30 days to form a new government.

BBC