New Zealander Nyika said he realised the medal had been stolen when he went to surprise a young fan at their school two weeks ago, only to find the medal was missing.

"A kid dressed up as his hero, which happened to be me, for a mufti day at school so I thought I'd surprise him and stop by with my medal," he said according to Stuff.

"That's when I realised it was gone.

"I didn't notice until then.

"I just want the medal back.

"It's almost worthless to anyone but me, you know, so I really hope I can get it back.

"One of the best things about having the medal is being able to go to schools and show it to kids, and now I can't do that.

"I was pretty embarrassed about it, but people have made me realise that nobody has a right to go through your things, to steal your things.

"The police are doing a great job, and I'm confident they'll be able to track it down."

As reported by Radio NZ, the 22-year-old said the worst thing about the theft was that it occurred in his hometown of Hamilton.

"Pretty shocked and pretty peeved off," he said.

"I initially thought I'd just misplaced it, but I'd left it in my car just so I can take it around to family, friends and schools and that's particularly disappointing as that's [visiting schools] one of my favourite things about coming home from the Commonwealth Games, sharing it with my community.

"So it's really sad to have it taken away from me in my own community."

Police have released a number of CCTV images of people in a shopping centre in Onehunga and have said they are looking to speak to anyone with information.

"We want to speak to anyone who has information or was in the area at the time," detective sergeant Paul Slater of Hamilton Tactical Crime Unit said.

"We also want to speak to the people pictured as we believe they can help us with our enquiries.

"Obviously a Commonwealth Games medal is very distinctive and of high sentimental value to the victim and his family.

"Our priority is to return this medal to its rightful owner.

"We believe someone will know where it is or who these people are in these photos so we can speak to them."

Nyika beat Australia's Jason Whateley in Gold Coast to claim heavyweight gold.

Four years earlier he beat Kennedy St Pierre of Mauritius to the light heavyweight title at Glasgow 2014.