Questions have been raised after a man who was previously jailed for electoral fraud was reported to have been closely involved in Labour's Peterborough by-election victory that brought in a controversial new MP.

The party won the June 6 contest by 683 votes, despite its candidate, Lisa Forbes, having been revealed to have liked posts on Facebook describing Theresa May as having a “Zionist slave master’s agenda” and saying that Mossad was behind ISIS.

A Sunday Times investigation revealed that Tariq Mahmood - who was jailed for 15 months in 2008 and expelled from the party for his role in a “systematic campaign of electoral fraud” after forging postal votes - campaigned extensively for Ms Forbes.

Labour had previously insisted he had no involvement in the campaign.

Mr Mahmood, a 51-year-old former Labour local branch secretary in the constituency, also accompanied Jeremy Corbyn on a tour of local mosques, community centres and the high street in Peterborough days before the election and appeared in a Labour by-election video along with the Labour leader and candidate.

The Sunday Times also reported Mr Mahmood spent most of election day outside a polling station and was subsequently present at the by-election count, wearing a Labour rosette on both occasions. He denied any wrongdoing.

A Labour spokesperson told Peterborough Today: "Peterborough council, who organise the count, always announce the results in a public area of the venue.

"There were hundreds of people there. The Labour Party had 19 official guests who were allowed in to the restricted areas. He was not one of them."

“Members of the public can of course support Labour, but this individual did not play any role in Labour’s campaign.”

Cambridgeshire Police are also investigating five separate allegations of electoral fraud in Peterborough. Labour has labelled the allegations "false and baseless".

A party spokesperson told the JC: "These allegations are false and baseless. This person isn't a Party member and was not involved in the running of Labour's campaign or facilitating Jeremy Corbyn’s tour of Peterborough.

"Jeremy Corbyn is stopped in public places by thousands of people asking for photographs. The Labour Party did not ask supporters to be tellers on polling stations.”

During the campaign, Ms Forbes apologised for her actions on Facebook. Last week told a meeting of the Parliamentary Labour party that she wanted to reach out to the Jewish community.

However, the Peterborough Jewish community subsequently told the JC Ms Forbes had made no attempt get in touch.