Sadiq Khan MP, the controversial Labour frontbencher, has been accused of attempting to use a “union stitch up” to secure his party’s nomination for Mayor of London. Mr Khan ran the campaign to get Ed Miliband elected Labour leader with union votes, and The Sun claims he may now use the same trick to get the keys to City Hall.

A Labour source claimed Unions were ready to give him access to contact details of party members that his rivals would not have access to. The source said: “The whole thing is a textbook union stitch-up to rig the selection for Sadiq.”

Applications for the nomination open on 13th May, with Khan expected to compete against former Olympic Minister Tessa Jowell and the Tottenham MP David Lammy. He is polling second behind Jowell, in January he jumped eight points in a YouGov poll of Labour members.

With the support of Ed Miliband and the unions Khan could easily take the nomination. However, his candidature has led many in the capital deeply unsettled because of links to the convicted Al-Qaeda terrorist Babar Ahmed.

Khan has offered various contradictory explanations of their relationship, this has led to speculation that Ahmed was one of his closest friends as a teenager. The pair did meet at least once in Belmarsh Prison, which was secretly taped by MI6.

For years Khan campaigned to prevent Ahmed being extradited to the US to face terror charges. Ahmed maintained his of innocence, a position backed up by Khan. However, once he failed to stop the extradition he pleaded guilty in an American court.