Kelly Clarkson's divorce has taken a nasty turn - she has filed documents accusing her estranged husband of defrauding her out of millions.

The singer filed the papers, obtained by TMZ, with the California Labor Commission, claiming Brandon Blackstock, who also served as her personal manager throughout their marriage, overcharged her for his services.

Kelly alleges Brandon and his father Narvel Blackstock were not licensed to act as agents in California, but failed to tell her that while "demanding unconscionable fees,” “acting in conflict of interest” with her, “giving false information and/or making false representations.”

The star's attorney Edwin McPherson has called for all agreements with the Blackstocks and Brandon's company Starstruck Management to be declared "void and unenforceable".

Kelly was sued by Starstruck Management in September, claiming she owed them $1.4 million (£1.05 million) in commissions.

The firm's lawyer, Bryan Freedman, says, "It is unfortunate that Kelly is again attempting to avoid paying commissions that are due and owing to Starstruck to try and achieve some perceived advantage in her ongoing custody and divorce proceedings."

Kelly and Brandon previously fought over the custody of their two kids after Blackstock asked if they could stay with him on the family's Montana ranch. She demanded they stay with her in Los Angeles and a judge agreed with her.

Brandon can currently see the kids every other weekend.