Police made "major failings" when investigating allegations of electoral fraud and malpractice in Tower Hamlets during the London Mayoral elections in 2014, a London Assembly committee has said.
Former Tower Hamlets mayor Lutfur Rahman was forced to step down after an Election Court found him guilty of a litany of corrupt and illegal practices, but he has faced no criminal prosecution.
Steve O'Connell, chairman of the Assembly's Police and Crime Committee, said that there was "widespread concern" that despite the findings against Mr Rahman, the Metropolitan Police had not brought charges.
He said: "During our investigation, we, as a committee, have been shocked to uncover major failings by the Metropolitan Police in its ability to investigate allegations of electoral fraud and malpractice.
"Missed files of evidence; missed opportunities to gather witness statements; witnesses who were prepared to give evidence in the Election Court but were unwilling to do so in criminal proceedings - this is not what we expect from a supposedly world-leading police force."
Mr O'Connell has written to Sophie Linden, the Deputy Mayor for Policing and Crime, urging her to use her powers to call on Her Majesty's Inspectorate of Constabulary (HMIC) to look into the activities of officers investigating the election.
He wrote that more could have been done to examine the claims and that the investigations that did take place were not undertaken to the highest standards.
Mr O'Connell said that a bundle of 27 files sent to the Director of Public Prosecution was not reviewed by the force, and that there were missed opportunities to gather witness statements.
He wrote: "It is time therefore for a fresh pair of eyes to review the activities of the Met in regard of the allegations of electoral fraud and malpractice as they relate to the 2014 Tower Hamlets Mayoral election.
"While the time limited constraints of the Representation of the People's Act may prevent any prosecution of past electoral malpractice by Mr Rahman, offences of bribery, corruption and conspiracy have no time limit for bringing charges.
"There may still therefore be opportunities to mount a criminal prosecution and bring a sense of closure to what has been a systematic affront to the democratic process."