MP Aaron Gilmore threatened to get Prime Minister John Key to have a waiter sacked after the MP was refused more wine at a dinner at a National Party function at the weekend, a witness says.



Christchurch lawyer Andrew Riches, who witnessed Gilmore's outburst at a waiter on Saturday night says the MP told the waiter he would get the prime minister's office involved.



Riches confirmed Gilmore made a comment to the Heritage Hanmer Springs hotel waiter along the lines of: "Do you know who I am? I'm an important politician".



"He [Gilmore] threatened to have the prime minister's office intervene and end the waiter's employment," Riches said.

Key's office released a statement this afternoon saying such an allegation was a serious matter.



"My Chief of Staff has rung Mr Gilmore this afternoon and Mr Gilmore refuted the allegation. Mr Gilmore indicated that he did not believe that he used the words claimed in Mr Riches statement," it said.



Riches also attacked the "half-hearted apology" Gilmore issued today, saying he was incensed the MP was trying to "shift responsibility" for his poor conduct



Riches said he had been "unfairly tarnished" by Gilmore's conduct.



"By the time this incident occurred the remainder of our party had left the restaurant and were not connected to these events in anyway," Riches said.



"I consider attributing blame to any other person to be completely unjustified.



"I had hoped that this would be a private matter to be resolved between Mr Gilmore and the staff member involved.



"However given the level of media interest and the half-hearted apology of Mr Gilmore I consider it prudent to have the facts set out in full to prevent other persons being unfairly tarnished by the actions of Mr Gilmore."



The apology issued from Gilmore's office today said: "As a group of diners our behaviour was at times boisterous, and I sincerely apologise for any offence this may have caused to staff and/or patrons.



"On this occasion I believe as a group our behaviour fell short of this mark, and I should have recognised this at the time"



Key this afternoon told reporters he had accepted Gilmore's apology.



"I think it's a bit disappointing," he said.



"He [Mr Gilmore] was clearly involved in a group that was involved in some slightly unruly behaviour."



Riches, who left the waiter a note the following day expressing his embarrassment, said he was "happy to let Gilmore apologise".



"[Now] I've got the Prime Minister calling me a pisshead."



In a Facebook post earlier today Gilmore also added to his earlier apology.



Responding to an earlier post, he commented: "I want to also make it clear I do not believe that any of my friends were rude to the staff, despite the barman saying otherwise."