Kiwis who celebrated Waitangi Day in London have shamed an expat, who made his thoughts known to the Prime Minister and High Commissioner in a complaint, saying the misbehaviour has shamed New Zealand.

Dylan Clements, who has worked in London for four years, reported indecent exposure among Kiwis, some of whom urinated on footpaths and historic monuments, including Westminster Abbey, in the annual Waitangi Day Circle Line Pub Crawl on Saturday.

In his complaint, Mr. Clements claims he is not a prude, but the behavior of Waitangi Day revelers shamed him, as he had seen them misbehaved on underground platforms and used "vulgar" language in front of children and elderly people, the New Zealand Herald reported.

About 4000 New Zealanders celebrated on London streets on Saturday, moving from one pub to another.

Meanwhile, London police were reportedly surprised by the complaint, saying they looked forward to Waitangi Day celebrations in the capital because Kiwis were friendly.

"During the day there were no arrests that I'm aware of, no fights or specific recklessness," Westminster Borough Inspector Bruce Middlemiss told stuff.co.nz.

Inspector Middlemiss also told ONE News that details on the event might have been exaggerated.

"There was no unruly behaviour; they were 99% respectful when asked to stop doing something... On a scale of what we do on a week to week basis it was very minor," he said.

Nicole Dolamore, a Facebook user reacted to Mr. Clements claims via Facebook.

"To the egg who started all this negativity - I hope you are ashamed... You have misquoted people, misrepresented the facts and got it wrong every step of the way. I hope that you see the outrage and uproar that you have caused and think twice before making such allegations again."