NSW Police have arrested a man after he produced a gun north of Goulburn.

The 31 year old allegedly produced the weapon when he was stopped for a random breath test at Marulan in the early hours of new years day.

Police say the man produced the loaded semi automatic weapon and threw it to the ground.

He faces charges including not keeping a firearm safely, handling a firearm under the influence of alcohol and possessing an unregistered firearm in a public place.

He was refused bail to face court later this month.