Flamboyant former NBA star Dennis Rodman is expected to arrive in Pyongyang Tuesday, US media reported, with the heavily-tattooed former player apparently set for another round of his controversial "basketball diplomacy".

The eccentric ex-Chicago Bulls power forward made at least four visits to Pyongyang, most recently in 2014 when he attracted a deluge of criticism after being filmed singing happy birthday to his "friend for life" North Korean leader Kim Jong-Un.

The 56-year-old was spotted at Beijing International Airport Tuesday but declined to answer questions, CNN said, adding that two officials in North Korea confirmed Rodman was expected to arrive in Pyongyang later that day.

"He is going as a private citizen," a senior Trump administration official told Fox News.

The player known as "The Worm", is one of the few Westerners to have met Kim, who took over following the death of his father Kim Jong-Il.

It is not clear whether Rodman, who once dated Madonna and was married to model and actress Carmen Electra, will be meeting with Kim Jong Un during the trip, or what the exact purpose of the visit is.

He has previously described his trips -- including one in 2013 with the Harlem Globetrotters -- as "basketball diplomacy" but has been roundly criticised for failing to raise human rights issues or the plight of US missionary Kenneth Bae, who was detained at the time.

Rodman, who is known as much for his piercings, ever-changing hair colours and off-court antics as his court skills, has developed an unlikely relationship with the North Korean leader since making his first trip there in 2013.

The bombastic player -- who once wore a wedding dress to promote one of his books -- also knows US President Donald Trump, having appeared as a contestant on Trump's pre-presidency reality television show "Celebrity Apprentice".

Trump called Rodman "smart" for his 2013 trip to North Korea, NK News reported.

"It’s not an act. But he’s a much different guy and this year on the Apprentice — it's amazing how sharp and smart. Dennis is not a stupid guy. He’s smart in many ways; he’s very street-wise," Trump said in comments republished by Politico at the time.

The young Kim, who was educated in Switzerland, is reported to be a keen basketball fan and especially of the Chicago Bulls, for whom Rodman played a key role in winning three NBA titles alongside Michael Jordan in the 1990s.

The trip comes amid high tensions between Washington and Pyongyang -- which is currently detaining four Americans -- following a string of weapons tests by the North, which have prompted successive rounds of sanctions and caused the US to step up its own muscle-flexing in the region.

Rodman routinely distances himself from political events in the country.

Source: AFP