Ashton Kutcher's divorce from Demi Moore has reportedly turned nasty.

The estranged couple - who separated last November after six years of marriage following the Two And A Half Men' star's affair with 22-year-old San Diego-based administrative assistant Sara Leal - are said to be locked in a bitter battle over their enormous fortune.

"(They) are trying to negotiate a settlement out of court and out of the public eye. They still haven't reached an agreement over money, because Ashton earned substantially more during the final years of their marriage, but he doesn't want to pay a large settlement," a source told The New York Post.

The 34-year-old actor - who is currently the highest paid star on TV - is estimated to have banked $24 million since taking over the sitcom from Charlie Sheen - is worth $140 million, while Demi is worth $150 million. Another source close to the pair said, "The discussion could boil over into a public court battle."

Ashton was previously said to be refusing to budge on the financial terms of their separation and how they should divide their assets. A source said the actor is "so cheap" and is refusing to sign off on the paperwork so they can finally go their separate ways.

Ashton has already moved on from the actress and is reportedly living with his new girlfriend Mila Kunis, whom he has known for 14 years as they previously starred in the hit comedy series That 70s Show together.