A drug-addled Christchurch man's Queenstown stag party went wrong after he allegedly glassed his prospective best man and punched a groomsman, threatening to kill him with a butter knife, yesterday.

Sergeant Steve Watt said the group of five mates checked into a resort motel on Saturday and all appeared well until the evening.

"They were out on the town when the stag started to appear restless and agitated, and he was taken back to the motel," Mr Watt said.

"Two of the group arrived back about 5am, at which point the stag was still very anxious and restless, and ended up lashing out."

One of the freshly returned duo, the best man, was allegedly struck in the head with a glass.

The other was punched seven or eight times in the chest and stomach before the groom grabbed a butter knife and threatened to kill him.

The groom then ran off and was unable to be found by the group.

Two hours later the groom, a 27-year-old construction worker, was found and arrested by police.

Although he was immediately taken back to the Queenstown police station, he was not released on bail until about 3.30pm.

"Due to his intoxication level he was not released until well into the afternoon," Mr Watt said.

"We thought it wise to give him time to calm down."

The man will face three charges – assault with a weapon, common assault and threatening to kill – in the Queenstown District Court on July 16 but will appear before a registrar on Wednesday.

Mr Watt said the man was clearly under the effect of drugs, but was not given blood tests for readings or analysis of what drugs he was on, as per police practice.

"Drugs and alcohol certainly seem to have played a part in his actions, and the drugs were voluntarily taken. Being under the effect of drugs is no excuse for breaking the law, and does not change the facts of his actions – or the resulting charges."

When queried on the wedding date Mr Watt said he did not know when it was scheduled, but suggested a major restructuring of the groom's party might be in the wind.

"I think he'll be looking for a new best man," he said.

- © Fairfax NZ News