Kiefer Sutherland accused of headbutting NY designer

Kiefer Sutherland could be in trouble again after reportedly headbutting a man at a party to defend actress Brooke Shields.

"Party attack": Kiefer Sutherland at the NY gala

The 24 star was at a Costume Institute Gala after-party in New York when Proenza Schouler designer Jack McCollough allegedly knocked over the actress.

According to website TMZ.com, Sutherland saw it happen and told him to apologise. McCollough is said to have then pushed

Sutherland, who allegedly responded with a headbutt said to have broken the designer's nose.

Mary-Kate Olsen and Kirsten Dunst were said to be among the stars looking on as the incident