Defence Minister Ron Mark in scuffle over his cowboy hat at Fleetwood Mac tribute show

Defence Minister and New Zealand First MP Ron Mark has admitted he grabbed a man by his shirt in a scuffle over his cowboy hat. 

The incident occurred at a show on December 7 in Carterton. Mark was attending a performance by Seven Wonders, a Fleetwood Mac tribute band. 

Mark says "a man who'd had too much to drink" snatched his cowboy hat from behind him, then held it behind his back singing "haha". The man refused to give Mark his hat back - and so began the tussle. 

"When he refused, I grabbed his shirt which I probably shouldn't have done but I did, then he gave it back," Mark said. 

The minister had been at the show to celebrate his partner's birthday. 

"It was one of those schoolyard things you know, I remember in third form when the big kids used to steal my cap and then hold it behind their back and refuse to give it back to me - it was a bit like that. I got a little impatient so I grabbed his shirt."

Mark admits he had to hold himself back from going further.

"Sometimes you just really have to grit your teeth when you're a Member of Parliament," he told Newshub. 

"Just because someone has a public profile doesn't mean everyone's got licence to, you know, be a dick."

New Zealand First leader Winston Peters is backing his MP. 

"I'd do something about it if he'd stolen my hat," Peters said. "I'd make sure he didn't feel like stealing another hat for a long time, that's what I'd do."

According to Mark, the pair eventually apologised to each other. 

"He gave it back eventually and later on in the evening we caught up with each other and he apologised I apologised."