Members of the London Assembly have accused the police of ‘major failings' in their investigation of electoral fraud in Tower Hamlets.
A report from the assembly's police and crime committee has called for an inquiry into the Met's probe of the borough's 2014 mayoral contest.
Committee chairman, Steve O'Connell, said he was ‘shocked to uncover major failings' by the Met in its investigation.
The report said ‘more could have been done' to investigate the allegations of fraud and malpractice before and during the election.
It also found the investigations that did take place were not ‘undertaken to the highest possible standards'.
The committee found important evidence was missed by the Met, including a bundle of 27 files sent to the director of public prosecution that was ‘not reviewed' by police.
It claimed the Met could have ‘generated sufficient evidence' to seek a criminal prosecution had they carried out a more thorough investigation.
Mr O'Connell said: ‘This is not what we expect from a supposedly world-leading police force.
‘We urge the deputy mayor to use her powers to press for HMIC [Her Majesty's Inspectorate of Constabulary] to take the matter further, with the aim that eventually we can assure Londoners - and particularly residents in Tower Hamlets - that justice has been done.'
Tower Hamlets mayor John Biggs, who was elected in 2015 after Lutfur Rahman was found to have breached election rules, said: ‘Despite a High Court judge finding Lutfur Rahman and his colleagues guilty on multiple counts of corruption and electoral fraud, there is deep frustration that the process stopped without criminal charges.
‘On the basis of the evidence in the election court there were many leads to follow.
‘Many people in Tower Hamlets are understandably mystified why those who tried so hard to steal the 2014 election have yet to be fully held to account.
‘Thankfully electoral fraud is rare but where it does happen we need confidence that the police have the skills and motivation to thoroughly investigate and bring those responsible to justice.'