Prime Minister John Key says he did not offer to pay an unemployed Wellington man's dinner bill in 2012. But the disputed matter is heading to court.

A restaurant-goer arrested for trying to put his dinner and drinks on Prime Minister John Key's tab is seeking $10,000 compensation from police - and he wants the PM to be his key witness.

Wellington man Kent Boyd claims Key's Diplomatic Protection Squad (DPS) over-reacted in an "abuse of power", leading to Boyd being locked up in police cells overnight following a bizarre chain of events that stemmed from a dinner at the Green Parrot Cafe four years ago.

Boyd and a friend claimed they chatted with Key when they crossed paths at the Green Parrot - a popular haunt for politicians - on December 17, 2012. When Key asked what they did for a living, they told him they were unemployed.

MAARTEN HOLL/STUFF Wellington man Kent Boyd is seeking $10,000 compensation from police for a night he spent in the cells after a bizarre disagreement over whether the prime minster would pay for his dinner.

Boyd ask Key to put their mixed grills and beers on his tab and claimed Key agreed. But when Boyd went to leave, staff did not believe his claim that the prime minister would be picking up the bill.

Key's office says the prime minister did not offer to pay.

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ROB KITCHIN/STUFF The Green Parrot Cafe on Taranaki St in Wellington is a popular haunt for politicians such as NZ First leader Winston Peters. It was also the scene of dinner dispute in 2012 involving Prime Minster John Key.

An Independent Police Conduct Authority (IPCA) report in 2013 found Key's DPS staff did not use excessive force. It shows they were asked for assistance, and assessed Boyd and his friend as drunk and disorderly.

The DPS pulled the men aside and held them, calling Wellington Police, who arrested the pair and locked them up overnight for breaching bail and theft of the $82 meal.

Boyd was on bail that night over a past conviction and one of his conditions was to not be drunk in public. He claims he passed a drink-driving breath test at the police station but was held anyway.

Within days of the incident, the police had withdrawn the theft charge against him. A judge also found no breach of bail occurred.

In June, Boyd filed a civil case against the Attorney General, on behalf of the police, claiming he did not get the chance to ask Key to back up his claim before the DPS pulled him aside, and that he did have sufficient funds to pay the bill but was arrested before he got the opportunity.

His lawyer Chris Nicholls has written to Key's office multiple times since April requesting a formal statement for the court that includes the prime minister's recollection of events.

In response, Key's chief of staff Wayne Eagleson wrote to Nicholls, saying he understood there was a potential settlement offer forthcoming from police and it would be "premature" for Key to become involved.

Nicholls wrote back, multiple times, attaching a letter from the police's legal team confirming there was no settlement offer on the table and warning he may file a summons for the Key to appear as a witness at trial. He is yet to get a response.

"The PM is perfectly entitled to not respond, but at the end of the day he has been a witness to an event and I have asked him for information that would assist in the resolution of the dispute," Nicholls said.

A spokesperson for Key said on Monday that he did not offer to pay the bill and had not been summonsed to appear as a witness, but "should that occur, he would deal with the matter at that time."

"Although it was some time ago, the Prime Minister recalls being at the restaurant on the evening in question. The Prime Minister did not offer to pay for the men's meals and has no knowledge of how their bill was paid."

Police said on Monday they denied the allegations made by Boyd and would be defending the proceedings filed.

The Green Parrot's management did not want to comment.

The IPCA would not supply witness statements to Nicholls, aside from one email exchange between Wellington Police staff who dealt with Boyd's initial complaint.

It said Boyd had showed officers fingermark bruises on his arm and they offered to investigate the man-handling claim. But Boyd refused, saying he wanted compensation from police and an apology from Key instead, adding that he voted for Key and respected him.