The surprise move came after his supporters had announced plans for a big protest rally on 15 January, when the verdict and sentence had been due.

Navalny, who is under house arrest, blames President Vladimir Putin for widespread corruption.

His brother Oleg is also on trial. Both are accused of defrauding two firms.

Prosecutors are demanding 10 years in jail for him and eight years for his brother.

The brothers deny the charge that they stole 30m roubles (£338,500; $526,000) from the firms, one of which is an affiliate of French cosmetics giant Yves Rocher.

Alexei Navalny is the opposition figure the Kremlin fears most. A charismatic anti-corruption campaigner turned political activist and a vocal critic of Vladimir Putin.

He was one of the leaders of the anti-government street protests that engulfed the Russian capital three years ago. The case against him is widely seen as politically motivated.

He is on trial for fraud and money-laundering - charges he has described as ludicrous and as lies. And because his brother is on trial too he has accused the authorities of trying to take his family hostage to get at him.

The verdict was to have been announced on 15 January, but in a move that defence lawyers claim is unprecedented it has been brought forward at short notice. That appears to be an attempt to forestall street protests - tens of thousands of people had pledged to attend a rally in support of the brothers in January.

The new court date comes on the eve of new year, Russia's biggest holiday, which for most people lasts more than a week.

Alexei Navalny led mass protests against Mr Putin in 2011. He has faced a string of criminal charges, which he says are fabricated to neutralise his political influence.

His house arrest resulted from a five-year suspended sentence he received for the alleged theft of 16m roubles from a timber firm in 2009.

Social media organiser

In a tweet on Monday he announced "sentence tomorrow at 9 in the morning [0600 GMT]".

And in a statement on his blog, he said ironically: "It turns out that for good people exceptions can always be made." He was responding to supporters' astonishment that the date of sentencing had been brought forward.

A spokeswoman for Moscow's Zamoskvoretskiy court, Yulia Petrova, said later that "the sentence will be pronounced for the Navalnys on 30 December because the sentence has already been drawn up".

The reading of the verdict and sentence is likely to last several hours.

In 2013 Alexei Navalny came second in Moscow's mayoral election, supported by 27% of voters.

Shunned by Russia's main state-owned media he has mobilised thousands of supporters on social media. His supporters have now brought forward their rally to 19:00 (16:00 GMT) on Tuesday. They plan to hold it in Moscow's Manezh Square, near the Kremlin, an announcement on Facebook said.

The Facebook page announcing their previous plan to protest en masse on 15 January was blocked, at the request of prosecutors.

(BBC)