By Jeremy Laurence and Jack Kim
SEOUL (Reuters) - South Korea said on Wednesday world leaders visiting Seoul for a nuclear summit next week will discuss North Korea and Iran's "illegitimate" atomic activities, angering the North that said such talk would be a "declaration of war".
Foreign Minister Kim Sung-hwan told Reuters that while nuclear weapons and proliferation issues were not on the formal agenda at the Nuclear Security Summit in Seoul from Monday, Iran and North Korea would clearly be key issues on the sidelines.
"There is no question that international community has serious concerns about the illegitimate nuclear activities of North Korea and Iran," he said in a written interview.
"As major leaders including leaders of the participating countries in the six-party talks will attend the Seoul summit, the North Korean nuclear issue will naturally be discussed on the separate occasions such bilateral talks on the margins of the summit," he said, adding dozens of such meetings had been planned.
Along with South Korean host President Lee Myung-bak, leaders from four other six party states -- U.S. President Barack Obama, China's Hu Jintao, Russia's Dmitry Medvedev and Japan's Yoshihiko Noda -- will be in Seoul for the two-day summit.
North Korea will not attend the summit and its pursuit of nuclear program and ballistic missile program had not been on the formal agenda, but the announcement of a long-range rocket launch in April is now expected to take centre stage.
North Korea will consider it a "provocation" if its "nuclear issue is placed on the agenda at the Seoul summit" and if any statement is issued against the North for pursuing such a program, its official KCNA news agency said.
"Any provocation will amount to a declaration of war against the DPRK (North Korea) and result in throwing a stumbling block in the way of discussing the denuclearization of the peninsula," it said on Wednesday.
Lee is expected to urge China's Hu to use his influence with North Korea to stop the planned rocket launch, which it says will put a satellite into orbit to mark the birth centenary of the state's founder Kim Il-sung.
Experts say the launch is clearly a ballistic missile test, banned by U.N. resolutions and it would likely undermine an agreement last month between Pyongyang and Washington to suspend such testing to foster talks on resuming U.S. food aid.
China has already put rare public pressure on the North over the reclusive state's plan to launch the rocket, which cast fresh doubts on talks aimed at ending its nuclear ambitions in return for economic aid and diplomatic rewards.
The announcement last week of the rocket launch caused outrage among international powers which pressed the North to call off the move saying it would deepen tension and further isolate it.
The North has twice tested a nuclear device, but experts doubt whether it has the ability to miniaturize an atomic bomb to place it atop a warhead.
North Korea is believed to have enough fissile material to make up to a dozen nuclear bombs, and in 2010 unveiled a uranium enrichment facility, in addition to its plutonium program, which opened a second route to making an atomic weapon.
Kim said South Korea had shared its concern with six-party members about the rocket launch, and would try to dissuade the North from following through with its plan.
(Editing by Robert Birsel)