The development emerged after a court overruled his request to dismiss an election petition challenging the recent mayoral election.
According to a report in 'The Guardian', High Court judges Justice Supperstone and Justice Spencer on Tuesday said they had reached the firm conclusion, for reasons they would give at a later date, that the petition was "not a nullity in whole or in part".
Four petitioners, headed by Andy Erlam, who stood as a councillor on an anti-corruption ticket, had filed an election petition.
They sought cancellation of the election results following widespread allegations of fraud and intimidation, the London-based newspaper reported in its web edition.
They claimed Rahman’s team used a “variety of forms” of fraud when he won the mayoral election by 3,000 votes in May.
But lawyers for Rahman applied for the petition to be dismissed as an abuse of process. They said that in breach of the relevant rules, sufficient particulars of the allegations were not given, the report said.
However, the court granted the petitioners a trial and asked them to produce further particulars of the allegations in the petition by Aug 18.
The court also dismissed petitioners’ plea for the case to be heard outside Tower Hamlets.
The court said a commissioner, who will now be appointed to hear this petition, would fix the date of the hearing.
In the May election, Rahman's 'Tower Hamlets First' party swept the poll despite a government inquiry launched by Cabinet minister Eric Pickles.
According to media reports, the inquiry investigated claims that public money had been spent disproportionately on Rahman supporters' pet projects and that council properties had been sold to his allies at knockdown prices.
“The high court petition accuses Rahman of being connected to alleged electoral fraud, including the casting of postal votes in the names of people not entitled to be on the electoral register,” the Guardian said.
It also alleges that votes were illegally cast on behalf of other electors and that activists were paid to lobby people in and around polling stations.
“The petition claims false allegations of racism were made against losing Labour mayoral candidate John Biggs,” the Guardian reported.
The report said the courts might now investigate Rahman's election win, with the possibility of the result being overturned.
Rahman, however, dismissed the allegations levelled against him by the petitioners.
In a statement, he said there was no evidence that the recent election results were due to fraud and intimidation.
"It is clear that these complaints are being generated by disgruntled candidates who lost and the court has recognised this by not granting them a protected costs order," he said.