AceShowbiz - Mel Gibson's ex-girlfriend has broken her silence about her ongoing legal battle with the "Braveheart" star to defiantly threaten the actor/director with a court showdown. Gibson and singer Oksana Grigorieva split in early 2010 and have been waging a bitter feud over the custody of their baby daughter Lucia ever since.

In recent weeks, the legal spat turned really nasty when audio of Gibson hurling insults at his ex as she accused him of attacking her and knocking out a tooth was leaked to the media. The movie star countered by claiming his ex had tried to extort him over the taped phone audio.

Police in Los Angeles are currently investigating both Grigorieva's domestic violence claims and Gibson's extortion allegations. Neither has spoken to the media about the ongoing battle - until now. Grigorieva lost her cool when she was asked for an update during a paparazzi encounter in Los Angeles on Friday, July 23.

She raged, "Mel is lying. He's lying. There's no extortion... I'm fighting for my child. He's just a liar, and it will come up in the court, just wait." The singer also used the paparazzi encounter to dismiss new reports her sister leaked the infamous phone tapes to the media, stating "She doesn't have them. She erased them a long time ago."

Meanwhile, Grigorieva's representative tells U.S. news show Entertainment Tonight, "Oksana emphatically denies that anyone on her side, specifically her sister, leaked or marketed (the tapes)."