TBILISI, September 12, 2008 (AFP) - Georgian President Mikheil Saakashvili will face 'tough questions' over his handling of the crisis with Russia, a top politician said Friday, joining opposition criticism of the Georgian leader.

Nino Burjanadze, a two-time interim president and former speaker of parliament, called for an independent investigation into the events leading up to Georgia's five-day war with Russia last month.

'There is a time for tough questions. Of course what happened was a Russian provocation, but we need to know whether it was possible to not yield to this provocation,' she said at a news conference.

'Serious analysis and a comprehensive investigation must be carried out to establish the truth about events preceding the crisis.'

After weeks of silence during the conflict, Georgia's vocal opposition has begun raising doubts about Saakashvili's handling of the crisis.

Burjanadze, a former ally of Saakashvili who resigned as speaker earlier this year citing 'mistakes made by the authorities,' also said she was planning to form a political party to challenge the government.

She described the situation in Georgia as 'extremely critical,' and said that Georgia could not count on Western support alone to resolve the crisis.

'Georgia enjoys extraordinary support from the West, but the resources the West has to support Georgia are not unlimited,' said Burjanadze, who returned to Tbilisi this week after a tour of Western capitals.

Wary of appearing unpatriotic, opposition leaders in Georgia announced a moratorium on criticising Saakashvili at the beginning of the crisis, which saw Russian troops and tanks pour into Georgia after the Georgian army attempted to retake the breakaway region of South Ossetia.

But with Russian forces preparing to withdraw to South Ossetia and another rebel region, Abkhazia, Saakashvili has faced increasing criticism.

At a press conference this week, opposition New Rights party leader Davit Gamkrelidze called for Saakashvili's resignation, saying 'he must resign and a date for snap presidential and parliamentary elections should be announced.'

Georgian media have reported that the United Opposition Council, the main challenger to Saakashvili in this year's parliamentary and presidential elections, is in talks on how to challenge the government and will unveil a plan next week.

Some opposition leaders have said they could call for a return to mass street demonstrations. Tens of thousands of Georgians took the streets last year for anti-government protests, forcing Saakashvili to call a snap presidential election after riot police violently dispersed demonstrators.

Divided and lacking a charismatic leader, Georgia's opposition has repeatedly failed to mount a serious challenge to Saakashvili since he swept to power after the peaceful protests of the Rose Revolution in 2003.

Saakashvili won January's snap presidential vote in a single round of voting and his United National Movement party swept parliamentary elections a few months later.

But analysts say Burjanadze, once a Saakashvili loyalist, is one of the few Georgian politicians with the clout and experience to mount a serious challenge.