Authorities blocked Farrow from holding a genocide memorial ceremony yesterday at a Khmer Rouge prison to draw attention to send a message to China to pressure Sudan to end abuses in Darfur.
Cambodia has close ties to China. The Cambodian government had said days ago it would prevent Farrow from going through with the ceremony.
Farrow and her group arrived at a barricade and refused to go away.
Police started pushing the group, which eventually got into a car and drove off. No one was hurt.
Farrow could not be reached for comment.
