George Galloway has been accused of having a supporter pose as his rival candidate’s dead father in order to obtain her marriage certificate and smear her as a liar.

The battle for Bradford West descended to a new low after the Respect candidate launched a series of personal criticisms against Labour candidate Naz Shah. Mr Galloway is defending a 10,140 majority in Bradford West, which he took from Labour in a by-election three years ago.

At a hustings in Bradford on 8 May, Mr Galloway brandished what he said was Ms Shah’s wedding certificate, claiming she had lied about being forced into marriage at 15 – when she had in fact been 16 and a half.

Ms Shah has spoken openly about the tumultuous upbringing which inspired her to go into politics, beginning with her father eloping with a 16-year-old neighbour when she was just six. At 12 her mother sent her to Pakistan to protect her from a drug dealer who had helped buy the family a house and expected sex in return. When Ms Shah was still a teenager, her mother went to prison for murdering the man after years of abuse, leaving a young Naz to bring up her sisters alone.

In interviews she has also described being forced into a violent marriage at just 15 while she was in exile in Pakistan. But Mr Galloway used the hustings to accuse her of lying about her past.

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Producing what he said was her marriage certificate, to cheers from his supporters, he said: “You have only a passing acquaintance with the truth. You claimed, and gullible journalists believed you, that you were subject to a forced marriage at the age of 15. But you were not 15. You were 16 and a half.”

Ms Shah strongly denies this, saying she had two ceremonies, one at 15 and a second at 16, to make sure that their marriage would be legal in Britain. She is seeking documentary evidence in Pakistan to prove the first marriage ceremony.

Her supporters believe someone acting for Mr Galloway posed as her dead father in order to obtain the Islamic wedding certificate – the nikah.

Mr Galloway’s office vehemently denies this. Ron McKay, Mr Galloway’s spokesman, said: “He got the certificate from a close family member [of Ms Shah] and we authenticated it in Mirpur.” He discounted Ms Shah’s explanation, saying: “I have talked to the first husband who confirms she was 16 and a half and that there was only one wedding.”

Mr Galloway also used the hustings to accuse Ms Shah of having applied to represent Respect in Bradford East, just days before she was selected for Labour in Bradford West.

In response to the claims, a Yorkshire Labour spokesman said that all Mr Galloway’s allegations were false. “While George Galloway continues his disgusting sniping and smearing, Naz Shah will continue working hard to demonstrate to the people of Bradford West that she will be their advocate and the strong voice the community so badly needs to bring about real change.”