Mr Mallard told reporters after the committee that he believed a former staff member had left the office after being hit on the head. He said he had heard the allegation indirectly from "a very good source".
Speaking in Tonga yesterday, Mr Key said he accepted the word of his minister and she had said it did not take place. "She is not going to lie to a select committee."
Ministerial Services, which employs ministerial office staff, would not say if any former staff member of Ms Parata's claimed to have been hit. But it said that there had been a personal grievance from one of the staff who was employed in her office.