Flamboyant former NBA star Denis Rodman has become the most high-profile American to meet the new leader of North Korea, vowing eternal friendship with Kim Jong-Un at a basketball game in Pyongyang.

The man who once dated Madonna brought his charm to bear on the leader of the impoverished, isolated state, as the unlikely pairing sat together in a packed stadium for Thursday's game that ended in a diplomatic 110-110 tie.

"You have a friend for life," Rodman told Kim in a speech to the crowd, according to a statement by the New York-based VICE media company, which organised Rodman's trip to North Korea.

Pictures of the event showed Rodman in dark glasses and a baseball cap clapping and laughing next to a clearly delighted Kim, who was dressed in a blue Mao suit with a lapel pin bearing the likeness of his father Kim Jong-Il and grandfather Kim Il-Sung.

The pair were later photographed again joking together at a post-game reception hosted by Kim, where Rodman, sporting a pink neck scarf, appeared to be enjoying a martini.

Rodman's access to Kim, who took over the reins of power in North Korea after Kim Jong-Il died in December 2011, raised more than a few eyebrows among Pyongyang watchers.

A recent delegation to North Korea that included Google chairman Eric Schmidt and Bill Richardson, the former US ambassador to the United Nations, never got to see the young leader.

Rodman's visit came as the UN Security Council is still debating how to punish North Korea for carrying out a nuclear test on February 12 that triggered global outrage and condemnation.

In an enthusiastic commentary on the Kim-Rodman meeting, the North's official Korean Central News Agency (KCNA) said the former Chicago Bulls' star -- nicknamed "The Worm" -- said the current impasse in US-North Korean relations was "regrettable."

The US State Department said Washington had nothing to say about Rodman's trip.

"We don't have any details on all aspects of this trip. We weren't in touch with him before... it's not something we've taken a position on," said deputy acting spokesman Patrick Ventrell.

"Private American individuals are welcome to take the actions they see fit. We just don't have a position, this is a private American's travel," Ventrell said.