Kiefer Sutherland headbutted a fashion designer at a star-studded party in New York on Monday (May 3), it's been reported.

The 24 actor is said to have lashed out at Jack McCollough after the designer allegedly knocked over the actress Brooke Shields.

Kiefer asked Jack to apologise but the Proenza Schouler designer is reported to have responded by pushing the actor.

The 24 star then apparently retaliated with a headbutt.

Kirsten Dunst and Mary-Kate Olsen were among a host of stars present at the Costume Institute Gala when the alleged disagreement between the pair took place.

In a statement, Shields' spokesman told TMZ the designer “did absolutely nothing to her”.

“It's not clear what caused Kiefer to do what he did,” the spokesman said, before adding that he was unsure if McCollough had touched Brooke.

The actress is apparently due to be questioned by police about the incident later today (May 5).

Kiefer spent 48 days in a Californian jail two years ago after he pleaded no contest to a charge of driving under the influence of alcohol.