Ukraine's former Prime Minister Yulia Tymoshenko, a leading opposition figure, has been on trial since June for abuse of office over a gas deal signed with Russia in 2009. She could face up to 10 years jail if convicted.

Riot police moved back into place in side-streets near the courtroom in central Kiev on Tuesday in preparation for the resumption of the trial. Hundreds of Tymoshenko supporters have been camped out outside the courtroom throughout the summer in solidarity with her.

The administration of President Viktor Yanukovich says the gas deal, which Tymoshenko brokered, left Ukraine paying an exorbitant price for Russian gas supplies. Tymoshenko, who denies the charge, says her prosecution is a political vendetta by her arch-rival.

On the eve of the trial resuming, Prime Minister Mykola Azarov announced on Monday that Russia had finally agreed to review the 2009 gas contract, which Moscow has so far refused to do.

He gave no details, though a spokesman for the Russian gas giant Gazprom said in Moscow that talks were still continuing between the two sides. Yanukovich visited Moscow at the weekend for talks on the issue with President Dmitry Medvedev and Prime Minister Vladimir Putin.

The Tymoshenko trial, which has polarised public opinion in the ex-Soviet republic and caused street demonstrations against Yanukovich, was abruptly adjourned on Sept. 12 after the United States and European Union expressed fresh concern over her prosecution.

Since then, the EU has hardened its position further, warning Yanukovich it could scrap planned bilateral deals on free trade and political association if Tymoshenko is jailed.

Yanukovich's government, which says integration in the European mainstream is the bedrock of its foreign policy, hopes to initial these key agreements with the EU at a summit in December.

Before then he has to face top EU officials at a "partnership" summit in Warsaw on Sept. 29-30.

The EU says the Yanukovich leadership has responded favourably to a suggestion that it reclassify the charge against her so as to allow her to go free.

But his administration comprises hard-liners who want to see Tymoshenko extinguished as a political force.

Any changes to the law to "decriminalise" the charge against Tymoshenko is likely anyway to take weeks, perhaps months, to pass through parliament, observers say. And there are no signs of amendments to the law yet being drafted.

Commentators were divided over what might happen when the hearing resumes (1100 GMT) under judge Rodion Kireyev who placed the fiery Tymoshenko in police detention on Aug. 5 for "systematically" disrupting court proceedings.

The Tymoshenko camp says her defence counsel will make another plea for her release from custody during the trial.

Further adjournment was a possibility. Some observers thought Tymoshenko could be freed from trial detention to lighten the atmosphere ahead of Yanukovich's trip to Warsaw.

"There could be a (political) pause so as not to upset the Europeans before the summit in Poland on the 30th. Or perhaps there could be some symbolic action aimed at showing Europe that there is the possibility of a smooth solution to the court action against Tymoshenko," said political analyst Volodomyr Fesenko.

"No surprises can be excluded. But the authorities seem to be buying time while they look at various alternatives," said one Western European diplomat.

Tymoshenko's supporters say Yanukovich ordered the trial to neutralise her as a political opponent ahead of a parliamentary election in October next year.

But many commentators say it has turned into a public relations disaster for him, bringing not only criticism from the West but also from Russia, with which Yanukovich's government is trying to negotiate a new price for gas.