An emotional Dennis Rodman appeared to break down on Monday as he apologized on his return from a trip to the Democratic People's Republic of Korea, where he sang Happy Birthday to top leader Kim Jong-un.

The former NBA star was widely criticized for refusing to bring up the plight of a US missionary detained in the DPRK during his weeklong visit.

The former Chicago Bulls player was also accused of pandering to the DPRK authorities during the trip, which featured an exhibition basketball match involving other former NBA stars to mark Kim's birthday.

"I love my country, America, I love it and I will never trade it for nothing in the world," Rodman told reporters at the Beijing airport.

Former world heavyweight boxing champion Mike Tyson has described Rodman's actions as "treason".

Rodman said he wanted to "show people that no matter what is going on in the world, for one day ... not politics, not all this stuff", before launching into an apology.

"I am sorry. I am not the president. I am not an ambassador. I am Dennis Rodman. Just an individual, just showing the world the fact that we can actually get along and be happy for one day," Rodman said, before his voice broke and he put his hands to his face.

He was ushered through a heavy media presence by security and his entourage.

Rodman has developed an unlikely relationship with the DPRK leader since making his first trip there in February, when he declared Kim a "friend for life".

The former power forward, who was wearing dark glasses, a blue tracksuit top and orange scarf, was asked whether he raised the issue of Kenneth Bae, who is detained by the DPRK.

In an interview with CNN last week, Rodman delivered an angry tirade in which he appeared to suggest that the missionary merited his 15-year prison sentence.

"I'm sorry I couldn't do anything," Rodman said, in comments echoing those of his publicist last week.

"I'm sorry, it's not my fault. I'm sorry. ... I just want to do some good stuff, that's all I want to do, basketball, that's all," the player added.

Rodman was returning from his fourth visit to the DPRK in 12 months.

"It is amazing that I had the opportunity just to go to North Korea, and for the Marshal (Kim) just to give me an opportunity just to be in his presence and in his city," he said, adding that he will visit the DPRK again next month for "another game".

Kim, who was educated in Switzerland, is reported to be a huge fan of basketball and especially of the Chicago Bulls, with whom Rodman won three NBA titles alongside Michael Jordan in the 1990s.

Bae was arrested in November 2012 as he entered Rason, a port in the northeast of the DPRK.

Pyongyang said that Bae was a Christian evangelist who brought in "inflammatory" material.

AFP-Reuters