SEOUL, South Korea (AP) - North Korea’s military has warned South Korea to stay out of a U.S.-led initiative to stop the spread of weapons of mass destruction, while Seoul postponed plans to announce its participation after a surprise offer of dialogue by Pyongyang.

An unnamed North Korean military spokesman said Saturday that South Korea’s full participation in the Proliferation Security Initiative would be seen "as a declaration of undisguised confrontation and a declaration of a war against" North Korea.

The warning, carried on North Korean state media, was not new. But it highlights Pyongyang’s sensitivity to the issue and comes amid rising tensions on the Korean peninsula after the communist North launched a rocket on April 5 despite repeated international warnings.

The PSI, which began in 2003, is aimed at deterring states such as North Korea and Iran from trade in missile and nuclear technology.

South Korea, which has been an observer, had planned to officially announce its full participation Sunday, but decided on a delay following the North’s proposal of a meeting about a troubled joint industrial zone across the border in North Korea, a Foreign Ministry official said Saturday on condition of anonymity, citing department policy.

The official did not elaborate, but Yonhap news agency quoted unnamed South Korean officials as saying the delay was aimed at reviewing "factors like inter-Korean talks," but did not mean that South Korea would cancel its plan to join the program.

Unification Ministry spokesman Kim Ho-nyeon told reporters that North Korea proposed a meeting with South Korean officials at the Kaesong Industrial Complex for Tuesday, but that it was not clear exactly what it wanted to discuss. Kim said South Korean officials were reviewing the proposal.

South Korea’s Dong-a Ilbo newspaper reported that the North wanted to discuss the case of South Korean man who has been detained at the complex for allegedly denouncing the North’s political system last month.

South Korean officials have repeatedly called on the North to grant access to the man, but the North has refused to do so, without providing any specific reason.

The complex has been considered a promising example of inter-Korean cooperation, combining South Korean technology and management expertise with cheap North Korean labor. It is also the last remaining major joint project between the rival Koreas, whose relations have been strained since conservative President Lee Myung-bak took office in Seoul last year with a tougher line on the North.

North Korea last week reacted angrily to the U.N. Security Council’s condemnation of its rocket launch, saying it would restart its nuclear program, expel international monitors and quit six-nation disarmament talks.

U.N. and U.S. monitors subsequently left the communist nation. Their pullout leaves the international community with no onsite means to monitor North Korea’s nuclear facilities, which can produce weapons-grade plutonium if restarted.

Pyongyang insists it sent a satellite into space, but regional powers say nothing reached orbit and the launch was actually a test of long-range missile technology.