An east London mayor has been removed from office and a poll declared void after he was found guilty of electoral fraud.

An Election Commissioner concluded Bangladesh-born Tower Hamlets mayor Lutfur Rahman breached election rules and must vacate his post immediately.

Four voters alleged he used "corrupt and illegal practices" in last year's election, which must now be re-run.

Rahman, who denied any wrong-doing, has been banned from standing again.

At the special High Court hearing, Election Commissioner Richard Mawrey also ordered Rahman to pay £250,000 in costs.

One of Rahman's aides Alibor Choudhury was also found guilty of corrupt and illegal practices.

Tower Hamlets First,  Rahman's party, said the judgement was a "shock" and it was seeking further legal advice in relation to a judicial review.

'Ruthless ambition'

Mawrey - who sat as a judge - said the mayor had "driven a coach and horses through election law and didn't care".

He added that Rahman, who had been elected for a second term in the borough, would be "incapable" of standing in the new election.

In the Election Court judgement, Mawrey said the effect of his ruling that Rahman's election was void meant that that it was as if the election "had never taken place" and he had not lawfully been mayor since that date.

Mawrey also added: "The evidence laid before this court... has disclosed an alarming state of affairs in Tower Hamlets.

"This is not the consequence of the racial and religious mix of the population, nor is it linked to any ascertainable pattern of social or other deprivation.

"It is the result of the ruthless ambition of one man."

Mawrey also described Bangladesh-born Rahman as an "evasive and discursive witness whose evidence was untruthful on occasion" and suggested he had played "race" and "religious" cards.

 Rahman ran a "ruthless and dishonest campaign to convince electorate his rival John Biggs was a racist", Mawrey said.

After the ruling, Labour London Assembly member Biggs said: "By setting out to break the rules and going to extraordinary lengths to win last May's mayoral election, Lutfur Rahman and his allies robbed the people of Tower Hamlets of the free and fair mayoral election they deserved and betrayed everyone in our community who trusted and voted for him."

BBC London's political correspondent Karl Mercer said it was likely that a new mayoral election would be held in June.

'Deliberately false allegations'

The group of voters who brought the action was headed by Andy Erlam, who stood as a councillor.

He said: "It is a fantastic result for democracy. There will have to be a new election of mayor.  Rahman cannot stand."

The four voters mounted the legal challenge under the 1983 Representation of the People Act.

Their lawyers made a series of allegations, including "personation" in postal voting and at polling stations and ballot paper tampering.

BBC News correspondent Sarah Campbell said the Election Commissioner had upheld a number of the allegations, including:

• Voting fraud: ballots were double-cast or cast from false addresses
• False statements made against  Rahman's rival  Biggs
• Bribery: grants approved to organisations which  Rahman favoured, most of which were run by Bangladeshi groups
• Treating: providing free food and drink to encourage people to vote for  Rahman
• Spiritual influence: voters were told that it was their duty as Muslims to vote for Rahman.

Lawyers for Rahman, who was re-elected for Tower Hamlets First last May, described the claims as "invention", "exaggeration" and "in some cases downright deliberately false allegations".

However the Election Commissioner said that Tower Hamlets First was "never really a party but the alter ego of Lutfur Rahman".

The Election Judgement said Choudhury, who was also found guilty of illegal practices, must immediately vacate his seat as a councillor and a new by-election must be held in the Stepney ward.

In a statement, Tower Hamlets First said: "Today's judgement has come as a shock - the Mayor strongly denies any wrongdoing and had full confidence in the justice system, and so this result has been surprising to say the least."

Communities Secretary Eric Pickles said the Election Court's judgement justified his decision to send commissioners into the council last year to take over some operations.

He said: "This judgement vindicates our action to intervene."

He added that the judgement against Rahman could mean extra powers being handed to commissioners and added the Met Police "also need to take steps to stop further corrupt practices".

Mayor of London Boris Johnson said: "I'm very glad that justice has taken its course and that a cloud has been lifted from Tower Hamlets."