The ongoing dispute between pop star Kesha and her former mentor Dr Luke just took an unexpected twist. It has emerged that the 29-year-old singer has dropped her California lawsuit against the producer she accuses of sexual assault, but will continue her court battle in New York.

According to Kesha's lawyer, Daniel Petrocelli, the dismissal was filed so the Tik Tok star could focus her legal efforts on the Big Apple, where she is suing Dr Luke for sexual assault, battery, harassment and emotional distress. She is also seeking to invalidate her recording contract with him and his label, Kemosabe records.

In February, Kesha lost a bid to end her contract with the music producer after Manhattan Supreme Court Judge Shirley Werner Kornreich refused to let her walk away from a six-album deal with Sony.

The Los Angeles native's career has been in limbo since she launched the lawsuit and Petrocelli said she is keen to get things back on track. In April she released True Colors, her first single in three years. "We have conveyed to Sony and the label Kesha's strong desire to release her next album and single as soon as possible," Petrocelli wrote.

Dr Luke, who has worked with the likes of Britney Spears and Katy Perry, has always maintained his innocence, describing the allegations as "defamatory" and claiming they have been contrived in an attempt to obtain a new recording contract.

He is one of Sony's biggest hitmakers and has the rights to produce at least six songs on each of her albums and could pursue damages if he does not.

"If Kesha is voluntarily dismissing her claims in the California case, it is because she has no chance of winning them," Dr Luke's attorney, Christine Lepera, wrote in a statement. "Kesha never should have brought her false and meritless claims against Dr Luke in any court."

Timeline of Kesha/Dr Luke drama

October 2014 − Kesha launches a lawsuit against the top music producer after accusing him of rape, sexual, verbal and emotional abuse.

December 2015 − Fans launch #FreeKesha campaign with petition asking Sony to release her from a contract that forces her to work alongside Dr Luke.

Dr Luke denies the allegations, stating: "All of their horrific allegations of abuse, threats and other purported misconduct by me against Kesha are completely untrue and deeply hurtful."

February 2016 − She loses her bid to end her contract with the music producer after Manhattan Supreme Court Judge Shirley Werner Kornreich handed down a ruling refusing to let her walk away from a six-album deal with Sony.

Days later, superstar Taylor Swift donated $250,000 (£176,000) to the singer to help with her financial troubles.

April 2016 − The Tik Tok hitmaker hints in an Instgram post that she was offered her freedom from Sony if she publicly apologised and recanted her rape allegations against Dr Luke.

May 2016 Kesha apologises to her fans after being 'banned' from performing a cover of Bob Dylan's song It Ain't Me Babe at the Billboard Music Awards 2016. She later performs it onstage with Ben Folds in LA.

August 2016 − Kesha drops assault claims against Dr Luke in Los Angeles, but not New York.