DENVER (Reuters) - A woman who punched, scratched and slid her buttocks against a $30 million painting by abstract expressionist Clyfford Still at a Denver museum has been sentenced to two years of probation, and will have to undergo mental health treatment, prosecutors said on Thursday.

Carmen Tisch, 37, pleaded guilty earlier this month to felony criminal mischief for striking at and leaning against the oil-on-canvas painting "1957-J No. 2" at the Clyfford Still Museum last year, the Denver District Attorney's Office said.

After causing an estimated $10,000 worth of damage to the painting, an intoxicated Tisch then pulled down her pants, slid her buttocks against the painting and urinated on the museum floor, prosecutors said.

A judge sentenced Tisch to two years probation and she must also undergo mental health treatment and receive help for alcohol dependency as a condition of her sentence. She may still face a restitution hearing.

The North Dakota-born Still was considered one of the most influential post-World War Two American abstract expressionist artists, but he was not as famous as contemporaries such as Jackson Pollock.

Still died in 1980, and Denver officials worked for decades with his widow, Patricia, to secure a single-artist museum featuring his works. When she died in 2005, she bequeathed her husband's collection to the city.

Four of his works were auctioned by Sotheby's for $114 million to endow the museum, which opened in late 2011.