Former basketball star Dennis Rodman is perhaps the only person in the world to call both US President Donald Trump and North Korean leader Kim Jong-un "friend".

The ex-Chicago Bulls power forward -- who has swigged vodka with Kim and been fired by Trump on "Celebrity Apprentice" -- believes the two unpredictable leaders "are pretty much the same people".

"They love control," Rodman told AFP Tuesday in Beijing, adding that warnings of nuclear peril are harmless "entertainment".

"Ain't nobody got no finger on the button."

As tensions grow between Pyongyang and Washington, Rodman, 56, has styled himself as an international peacemaker ready to help strike a deal.

He arrived in China Monday following stops in Tokyo and US territory Guam.

He hoped to arrange a trip to Pyongyang, which he has visited five times, but was stymied by a US ban against American citizens travelling to the country.

"We thought we would give it a shot while we're here," Rodman said, adding that he is working on obtaining a "special pass" from Trump to visit North Korea early next year.

While there, he plans to make a documentary and write a book about his relationship with Kim.

'Whole different dynamic'

Rodman believes he can "alleviate some pressures as far as communication"  between the US and North Korea.

On one of his North Korea trips in 2013 and 2014, "(Kim) gave me three things ... to say to the president," he said. "They asked us: Can you go back to America to ask them to do this for us?"

For years, Rodman kept these three "pretty reasonable" requests secret because Kim told him being a middleman might put him in danger.

But that was before Trump became president.

"This whole thing with me, (Kim) and Donald Trump -- it's a whole different dynamic right now," said Rodman.

"I said to (Trump) I got three things to say to you, and after that, he told me to fuck off."

Now, Rodman plans to organise a basketball game between players from North Korea and Guam, a Pacific island which the North has threatened to hit with missiles.

The match would be held in the "neutral site" of Beijing, Rodman said.

While he has yet to clear the idea with authorities, he hopes that such a game would "give something historical for everyone to see" -- to show that "there's no hatred at all" on either side.

'21st century guy'

Rodman -- who calls Kim the "marshal" and says the dictator dubbed him a "friend for life" -- has played drinking games, sung karaoke and ridden horses with the 33-year-old strongman.

He characterised the leader as a "21st century guy" who has had to bear the fallout of the decisions made by "tyrants" like his father and grandfather, North Korea's founding leader Kim Il-Sung.

"(Kim Jong-Un) is in a position where he probably wants to do a lot of things that are really positive," Rodman said.

"I think that the structure of the system just don't let him do it. I've seen that. You see him be happy, and then, all of a sudden you see him pull back. He wants to pull that trigger where he wants to let his people be more free."

Kim, a longtime fan of the Chicago Bulls, brought Rodman to his island and his ski resort, and even allowed the sportsman to hold his baby daughter -- the first American to do so.

It is believed that Kim and his wife, Ri Sol-Ju, have three children.

The basketball star received a rousing welcome when he and Kim visited the birthplace of Kim Il-Sung, greeted by a line of children who sang and bowed to Rodman.

"Those kids don't know nothing about me, but they were probably told, 'Respect him, because our marshal loves being with him,'" Rodman said.

The two men's relationship has been largely apolitical.

According to Rodman, they sang rock 'n' roll songs and watched performances by Moranbong (a state-approved girl group), "smoked cigars" and "talked about all the normal stuff."

They even played "Horse", a two-player basketball game.

Kim "lives and breathes basketball", Rodman said. (AFP)