Police are investigating four new allegations of electoral fraud at scandal-stricken Tower Hamlets after the borough’s mayor was found guilty of corrupt practices.

Detectives have been tasked with reviewing allegations included in a 200 page court report that declared void the 2014 election victory of former mayor Lutfur Rahman.

Scotland Yard confirmed that the ‘exceptional circumstances’ of the case meant police had been granted an extension to the one-year time limit within which criminal proceedings must be brought.

However detectives will be unable to start a criminal investigation into a fifth allegation under laws requiring proceedings to be started within one year of an offence being committed.

The Metropolitan Police (Met) received 164 complaints of electoral malpractice at Tower Hamlets in the lead up to, during and after the election on 22 May 2014.

Police will now consider the new material in connection with 47 other allegations originally reported to police. Two people have already been cautioned following investigations into four allegations of electoral fraud at the town hall.

In a statement, the Met said: ‘The Met takes any allegations of electoral fraud or malpractice very seriously, as it is committed to ensuring a free and fair election. In the run up to the General Election on 7 May, the Met has worked closely with the Electoral Commission and all the local authorities to ensure it plays its part to protect the integrity of the electoral process in London.

‘The Met is proactively monitoring all information and intelligence and where there are the grounds it will take action to prevent offences from being committed.

‘It is vital to ensure the integrity of the democratic process, so across London on 7 May, and in Tower Hamlets on 11 June, the Met will have a policing operation in place, including additional officers on duty based at polling stations. This operation will include learning from the policing operation in Tower Hamlets on 22 May 2014.’

Rahman has consistently denied any wrongdoing and will challenge the court ruling.

He told supporters in London: ‘People in Tower Hamlets are smart. They did not vote because they were bribed, coerced or intimidated.

‘I was voted in on my record of delivering for the people of this borough where the political establishment,’ the Guardian reports.