The leader of the National Party is backing his newest MP, Sam Uffindell, after it was revealed he violently assaulted a 13 year old schoolmate when at King's College.

Sam Uffindell admitted he made a big mistake when he was 16 and punched a 13-year old boy multiple times. 

Before joining parliament he apologised to the now adult victim but omitted telling the leaders of the party about the incident. 

RNZ political reporter Katie Scotcher spoke to Charlotte Cook.