Citing two unnamed sources familiar with the discussions, the magazine said the hardening of North Korea's position was made evident during a meeting last month in Singapore of mid-level North Korean officials and US foreign policy experts.

Taking part in the meeting were Han Song-ryol, North Korea's deputy ambassador to the United Nations, and Choe Son Hui, the deputy director-general of the North American affairs bureau in the country's foreign ministry, the report said Thursday.

The US side was led by Joel Wit, a former US nuclear negotiator, and included Corey Hinderstein, vice president of the international program at the Nuclear Threat Initiative, the magazine said.

According to Foreign Policy, the North Koreans told US experts they were no longer interested in resurrecting the February 29 agreement that called for US food aid in return to North Korean nuclear concessions and said they were reconsidering their previous agreements to eventually denuclearize as well.

The February 29 agreement called for a moratorium on nuclear and missile testing, a return of international inspectors, and 240,000 tons of food aid, the report said.

The North Koreans also told the Americans they were thinking about whether or not to get rid of the September 2005 joint statement, the magazine pointed out.

That document committed North Korea to eventually getting rid of its nuclear weapons program.