Kevin Costner has blasted his estranged wife's "unreasonable" demand he pay a "whopping" $885,000 toward her legal fees.

The 68-year-old actor has been locked in a bitter battle with Christine Baumgartner - with whom he has children Cayden, 16, Hayes, 14, and 13-year-old Grace - since she filed for divorce in May this year, and the latest move in their legal dispute has seen the 'Yellowstone' star's team insist the amount requested is "nothing short of outrageous".

According to documents obtained by People magazine, Kevin's team stated Christine has already received "$405,000 in fees, including an award of $300,000 in legal fees ($200,000 in attorney’s fees and $100,000 in forensic accounting fees) on July 12" and "removed $105,000 for fees from Kevin’s accounts."

They added: "The Family Code requires the Court to assess whether the fees incurred and prospective fees are reasonably necessary.

"Although Kevin is the wealthier party with a higher cash flow than Christine, Christine is quite capable of contributing to her own attorneys’ fees."

The lawyers also argued the amount Kevin has paid in fees shouldn't be relevant to Christine's costs, branding her argument "nonsensical".

They noted: "Christine’s argument that Kevin has incurred more in fees than she was awarded and what she took from his accounts is not, standing alone, a valid basis for an award of additional fees to her.

"The amount Kevin has incurred cannot be the talisman of how much Christine should be awarded in fees...

"[Kevin] has been forced to spend substantial attorney’s fees as a result of Christine’s uncooperative conduct... He has had to repeatedly go to court to (successfully) obtain relief.

"Christine’s actions increased the fees incurred by not only Christine, but also Kevin.

"To use these fees as the basis for an argument that Christine needs more to level the playing field is nonsensical."

Last week, Judge Thomas Anderle ruled Christine must pay over $14,000 of her estranged husband's legal costs, which he claimed were accrued while trying to get answers about her understanding of their pre-nuptial agreement.

The judge noted in the ruling this is “certainly a case of consequence.”

Last month, a judge agreed with Kevin's proposed amount of child support, setting his monthly payments at $63, 209 - falling far short of Christine's request for $175, 057.