TIGER Woods' wife has upped the ante in their divorce battle, with reports claiming she is demanding as much as $US750 million.

In addition to the money, Elin Nordegren has abandoned her bid for joint custody and now wants to be the sole legal guardian of their two young children, US reports say.

Nordegren and Woods have hired top divorce lawyers as they negotiate their split over the bombshell revelations of golfer Woods' secret playboy lifestyle.

Swede Nordegren, who has hired a London law firm to fight it out with Woods' Florida attorneys, wanted $US750 million ($A900m) from the split, the Chicago Sun-Times reported.

It would make the split the most expensive celebrity divorce, eclipsing the $600 million settlement expected in actor Mel Gibson's divorce, which is still being finalised. Woods' fortune was valued as high as $1.2 billion in 2008.

The couple had reportedly been working towards a joint custody agreement, but the Sun-Times reported yesterday the separation had "turned extremely testy".

Nordegren, who has moved out of the couple's Florida mansion, has also refused to sign a lifetime "confidentiality clause" designed to ban her from giving tell-all interviews about their five-year marriage.

Meanwhile, Woods was reportedly seen last week on the golf course inside his gated Orlando community with a mystery blonde woman.

"Tiger was on the golf course the other day, hitting balls," a witness told Radaronline.

"He was with a very pretty blonde who looked a lot like Elin. She was sitting in the golf cart while he was playing."

Woods, who is at home struggling with neck pain, has committed to playing in a string of high-profile golf tournaments in coming months.

He has signed for the British Open in July as he tries to add another major title win to the 14 he has already.

His next contest is the US Open in California next month.