Kiev - Ukraine's parliament has rammed through legislation directly challenging President Viktor Yushchenko, placing the country's pro-West ruling coalition in jeopardy, local media reported on Wednesday.

A parliamentary faction led by Yushchenko's erstwhile ally, former prime minister Yulia Tymoshehnko, switched sides during a stormy Monday evening session to join with the pro-Russia Regions Party to approve a package of bills directly aimed at reducing the presidency to the status of mere figurehead.

The collapse of the Yushchenko-led ruling coalition in Ukraine has been brewing since early 2008 when Tymoshenko, a politician openly keen to replace Yushchenko as the country's political leader, came into increasing conflict with the president over economic reforms, and alleged corruption within each of their parties.

The de-facto Regions-Tymoshenko bloc amassed more than 300 votes in four separate parliamentary votes, more than the majority needed to override a presidential veto, and even allowing a rewrite of the constitution, by the rules of the
450-seat house.

The assembly of such a powerful effective majority in the usually- fractious legislature, known as the Verhovna Rada, is rare, and no Rada in the past has ever managed to collect 300-plus votes to confront a sitting president.

The legislation took from the president the ability to name a prime minister, minister of defence and foreign minister, giving parliament authority to pick candidates for the job.

The new laws also made possible the sacking of the chief of the SBU, the national spy agency, by a vote of one-third of parliament or more and gave parliament the ability to override a presidential decision to sack supreme court justices.

But in perhaps the most damaging change for Yushchenko's political future, the de-facto Tymoshenko-Regions voting bloc set down regulations for impeachment of a president by parliament.

The passage of this range of legislation by a 300-plus majority makes a constitutional challenge of them by Yushchenko impossible, according to some Ukrainian constitutional experts.

Were the new laws actually to be enforced - a possibility already denounced by Yushchenko allies and some scholars as unconstitutional - the net effect would be Yushchenko's near total political emasculation.

Only Yushchenko's own party Our Ukraine, by floor count 30 MPs, stayed loyal to the president, walking out in protest prior to the critical votes.

But even leaders of Yushchenko's close ally the National Self Defence Party, traditionally a group voting in lockstep with Our Ukraine, declared themselves no longer bound by obligations to the President and reserved the right to join any new ruling coalition.

Our Ukraine leaders told reporters late on Tuesday night that they would on Wednesday formally leave parliament's ruling coalition, a grouping including Our Ukraine, National Self Defence and the party of Yulia Tymoshenko.

The three parties had patched together a razor-thin ruling coalition with 228 votes in Ukraine's 450-parliament in elections in September 2007.

Since then, the house has struggled to pass legislation due to infighting between the ruling coalition's members, primarily over government appointments.

Leaders of all three parties have accused their theoretical allies of attempting to place people in top jobs not for the public interest, but for the personal gain of tycoon MPs.

Once formalized, Our Ukraine's exit from power would by constitutional statute oblige Yushchenko to appoint a caretaker government and give him the right to call new parliamentary elections if a new ruling coalition is not formed in one month.

Yushchenko is a strong supporter of market reform, early Ukrainian accession to NATO and Ukrainian accession to the European Union.

The more populist Tymoshenko has supported the same policies but with less enthusiasm, preferring to focus on pension hikes, reducing food prices and attacking tycoons controlling most of Ukraine's economy. (dpa)