"They (Pyongyang officials) ... indicated they would, at an appropriate time, invite IAEA officials including (its head) Mohamed ElBaradei to North Korea," Richardson told journalists in Tokyo.

They "reaffirmed their commitment to rejoining the Non-Proliferation Treaty, also adhering to IAEA safeguards," said Richardson, a one-time energy secretary and UN ambassador under former US president Bill Clinton.

North Korea suspended its membership in the nuclear NPT in 1993 and placed limitations on IAEA inspections. It withdrew from the treaty altogether in December 2002 and kicked out inspectors.

Richardson, now governor of the US state of New Mexico, came to Tokyo after his four-day tour of North Korea, where he met with top government officials, including Kim Yong-Nam, the Stalinist country's number two.