Anatoly Sobchak, the former mayor of St Petersburg, once one of Russia's best known "democrats", is back from an 18 months exile in Paris, where he was sheltering from corruption charges.

He has been given assurances that he will not be arrested.

His return of Anatoly Sobchak to Russia today will be interpreted in very different ways.

For his supporters it marks the welcome return to the political stage of one of Russia's most dynamic politicians.

His critics say that it is proof that anyone who has the right political protection is immune from arrest on corruption charges.

In the perestroika period Mr Sobchak, a law professor, was one of the best known "democrats" in Russia. He became the leader of the reformist movement in St Petersburg and Boris Yeltsin seriously considered him as his vice-presidential running mate for the 1991 elections.

St Petersburg did not prosper as much as Moscow

Instead, on the same day as Mr Yeltsin became president he was elected mayor of what was then Leningrad. One of his first moves was to lead the campaign for the city to be renamed St Petersburg.

However Mr Sobchak's clean image became tarnished during his term in office. He failed to be re-elected in 1996 and was charged with corruption involving property deals he had authorised while mayor.

On 7 November 1997 - the same day that the head of the provisional government, Alexander Kerensky, fled from the Bolsheviks 80 years before - he fled to Paris.

He said he had a heart condition which needed urgent treatment.

But there was confusion as to whether he was actually ill or not. He and his wife, Lyudmila Narusova, now a deputy in the duma, the lower house of the national parliament, gave differing versions of what was wrong with him.

They repeatedly alleged that there was a politically motivated campaign against him, which made it dangerous for him to return to Russia.

Mr Sobchak is returning after receiving guarantees from special prosecutor Vladimir Kazakov that he will not be arrested.

It has been noted that the current government is well-disposed towards him and that there are a number of St Petersburg politicians now in high positions.

They include the prime minister Sergei Stepashin and the head of the Federal Security Service (FSB, the successor to the domestic KGB), Vladimir Putin, who used to be his deputy.

Mr Sobchak has said that he intends to run for a seat in the Duma in December's parliamentary elections from a Petersburg constituency.

He may well succeed in winning a seat, but it is interesting to note that he is not talking about becoming mayor of St Petersburg again.

Despite its potential as Russia's "northern capital" and second city, St Petersburg conspicuously failed to flourish during his term as mayor, compared to Moscow.