Possible N.Korea power shift shadows Clinton in South

SEOUL (Reuters) - U.S. Secretary of State Hillary Clinton plans to discuss with South Korean leaders on Friday how to rein in North Korea's nuclear weapons programme, after warning of a possible power struggle in the secretive communist state.

The task has grown more daunting, Clinton said on Thursday, with the possibility of crisis over who may succeed North Korean leader Kim Jong-il, 67, who is widely believed to have suffered a stroke last August.

Talks among regional powers to try to push North Korea into giving up its attempts to build a nuclear arsenal, in exchange for an end to its pariah status and massive aid, have largely ground to a halt.

Speaking to reporters as she flew to South Korea, Clinton said "the whole leadership situation is somewhat unclear" in North Korea and that South Korea's government has "a lot of worries" how and when Kim might be replaced.

Kim is believed to have largely recovered from his illness but his health remains a major concern.

"If there is a succession, even if it is a peaceful succession ... that creates more uncertainty and it also may encourage behaviours that are even more provocative as a way to consolidate power within the society," she said.

Clinton landed in Seoul on the third stop of her Asia tour following weeks of increasingly angry rhetoric by the North and reports it may be preparing to test a long-range missile that is designed to reach Alaska but has never successfully flown.

She met South Korean and U.S. military leaders whose troops face the North's 1.2 million-strong army, most of it positioned near the heavily fortified border that has divided the peninsula for about 60 years. There are about 28,000 U.S. troops to support the South's 670,000 soldiers.

She will also meet President Lee Myung-bak as well as the country's prime minister and foreign minister.

SPECULATION ON KIM'S SUCCESSOR

Succession is one of the most closely guarded secrets in North Korea but intelligence officials have said the three men most likely to replace Kim, in power since 1994, are his eldest and youngest sons and a brother-in-law. There is also speculation he could be succeeded by a ruling group of his top aides.

In the past months, North Korea has reshuffled the leadership of its powerful military and cabinet while announcing elections for its parliament, all of which analysts said indicate a major realignment of the ranks in Asia's only communist dynasty.

But Kim, as the unquestioned leader, has no clear rival and reports in South Korean and Japanese media said he may be preparing his youngest son, Swiss-educated Kim Jong-un, to take a prominent role by placing him in the parliament.

Multilateral talks to try to push destitute North Korea into giving up its attempts to build a nuclear arsenal have largely foundered.

At the same time, North Korea has increased its sabre-rattling. On Thursday, it accused the United States of planning a nuclear attack and said it was ready for war with South Korea.

Clinton could announce as early as Friday her choice of Stephen Bosworth, a former U.S. ambassador to South Korea, to be the U.S. envoy to negotiations on ending the North's nuclear programmes, two sources familiar with the matter said.

(Additional reporting by Jon Herskovitz)

(Editing by Jonathan Thatcher and Dean Yates)