A Kim Jong Un lookalike said he was detained and questioned upon his arrival in Singapore, days before a summit between the North Korean leader and US President Donald Trump.

The Hong Kong-based impersonator, who uses the name Howard X, is in the city-state for summit-related promotions by a mall and seafood restaurant.

He said the police officers who stopped him at Singapore's Changi Airport yesterday, searched his bags and questioned him for about two hours before letting him go.

He claimed police told him to stay away from Sentosa Island and the Shangri-La Hotel. Kim and Mr Trump are to meet Tuesday at the Capella Hotel on Sentosa Island and Mr Trump is expected to stay at the Shangri-La during his visit to Singapore.

Howard X said the police asked if he had been involved in protests around the world, including those by pro-democracy activists in Hong Kong. He said he responded that he had been at the scene of Hong Kong demonstrations as a musician playing the drums.

The Hong Kong-based impersonator, who uses the name Howard X, is in the city-state for summit-related promotions by a mall and seafood restaurant. Picture: AP (AP)

Later, Howard X and Dennis Alan, a Trump impersonator, held hands and walked around Merlion Park, a popular tourist destination. Picture: EPA (EPA)

"However, I never rioted and don't plan to ever riot. I told him that I ... would never do this in Singapore because it is against your rules to protest," he told The Associated Press.

Demonstrations in Singapore can only be held in a designated area, the 0.9-hectare Hong Lim Park, and require park approval. All other gatherings require a police permit.

Later, Howard X and Dennis Alan, a Trump impersonator, held hands and walked around Merlion Park, a popular tourist destination.

They posed with mock chili and black pepper crab dishes and took photographs with curious passers-by.

"I'm here to stay. I don't think they will try and kick out the president. It wouldn't be good press for Singapore," Howard X said.

"Nobody started talking about a meeting between Kim Jong Un and President Trump until we suggested it at the Olympics," Alan added, referring to their appearance at the Pyeongchang Winter Olympics in February.

Howard X said the police asked if he had been involved in protests around the world, including those by pro-democracy activists in Hong Kong. Picture: AP (AP)

They posed with mock chili and black pepper crab dishes and took photographs with curious passers-by. Picture: EPA (EPA)

"It all started with us. If there's a peace prize that anybody should get, we should get it," he quipped.

Indonesian Janette Warokka thought the impersonators were the real deal.

"It's so shocking for me. I don't know why those two famous guys come here," she said.

Raul Rio, a teacher from Texas, managed to take a selfie with the pair.

"They certainly look like the real ones. It was fun to see them," he said.