Ukraine's ruling pro-Western coalition has officially collapsed, the speaker of the Ukrainian parliament says.

Below is an article published by BBC News:

President Viktor Yushchenko has been involved in a long-running dispute with Prime Minister Yulia Tymoshenko. 

The president's Our Ukraine bloc left the coalition earlier this month [September 2008]. Parliament now has 30 days to try to form a new ruling coalition.

If those efforts fail, Mr Yushchenko can dissolve parliament and call a snap election.

The Our Ukraine party pulled out of the coalition on 3 September [2008] after the Tymoshenko Bloc sided with the pro-Moscow opposition Party of Regions to pass several laws that Mr Yushchenko saw as a threat to his presidential powers.

"I officially declare the coalition of democratic forces... in Ukraine's parliament dissolved," parliament speaker Arseny Yatsenyuk announced on Tuesday.

Mr Yushchenko and Ms Tymoshenko led the 2004 Orange Revolution, which overturned the fraudulent presidential election victory of a pro-Moscow candidate, Viktor Yanukovych. But since then the two former allies have become bitter rivals, vying for power ahead of the 2010 presidential election.

Ms Tymoshenko leads the second largest group in the 450-seat assembly, after Mr Yanukovych's Party of Regions.