Pageant judges have crowned a new winner of Zimbabwe's 4th annual "Mister Ugly" contest, upsetting supporters of reigning champion and prompting claims of cheating.

Judges on Saturday chose 42-year-old Mison Sere, citing his numerous missing front teeth and a wide range of grotesque facial expressions, over William Masvinu, who had held the title since 2012.

Masvinu and his supporters mobbed the judges upon hearing their decision, claiming that Sere was "too handsome" to win and his ugliness wasn't natural since it was based on missing teeth.

Contestants on stage during the 2015 edition of the Mr Ugly competition. Tsvangirayi Mukwazhi / AP

"I am naturally ugly. He is not. He is ugly only when he opens his mouth," maintained Masvinu, gesturing at his rival.

"Do we have to lose our teeth to win? This is cheating," shouted another contestant, Patrick Mupereki.

There was pushing and shoving as the results were announced and insults were hurled at the judges.

Sere dismissed the critics as just "sore losers" as he pocketed the $500 in winnings.

"They should just accept that I am uglier than them," he said. "I hope to get a TV contract. I already moved around schools performing and showcasing my ugliness so this is a chance to make it on TV."

Pageant organizer David Machowa originally told the Associated Press that he began the contest to remove the stigma of ugliness.

"Looks are God given," he said. "We should all be proud of who we are."

The pageant involved three rounds of modelling, with individual and group struts down a catwalk of a Harare nightclub. This year's competition attracted a record number of 36 entries, compared to just five in 2012 when Masvinu began his winning streak.

Beauty pageants are popular in this southern African country and even though they are typically for women, scandal is not unusual. Earlier this year, Miss Zimbabwe winner Emily Kachote faced a backlash on social media, with Zimbabweans calling her ugly and undeserving of the crown.

She was later forced to step down when just two weeks into her reign, images surfaced of her posing nude — which incidentally also brought down her predecessor.