US concern over 'unclear' N Korea

South Korea wants US help to restart denuclearisation talks with North

Hillary Clinton voiced concern over North Korea's "unclear" leadership situation as she arrived in South Korea on the third leg of her regional tour.

The situation meant the US had to find a better strategy to influence the North, the US secretary of state said.

Her comments follow speculation over the health of leader Kim-Jong-il, after reports he had a stroke last year.

Mrs Clinton will discuss North Korea and its nuclear ambitions in talks with top leaders in Seoul on Friday.

South Korea is hopeful that the new US administration will be able to restart denuclearisation talks with Pyongyang, which stalled late last year.

But hours before Mrs Clinton arrived in Seoul, North Korea issued the latest in a series of warnings to its southern neighbour, stating that its troops were "fully ready" for war.

Her visit also comes amid speculation the North may be preparing to test-fire a long-range missile, something Mrs Clinton has called "extremely unhelpful".

Sabre-rattling

As she flew into Seoul, Mrs Clinton told journalists that it was important to get the six-party nuclear talks aimed at ending Pyongyang's nuclear ambitions back on track.

North Korea maintains one of the world's biggest standing armies

Mr Kim is not known to have named his successor and Western diplomats fear any leadership crisis could further raise tensions on the peninsula.

"Everybody is trying to sort of read the tea leaves as to what is happening and what is likely to occur, and there is a lot of guessing going on," Mrs Clinton said.

"Our goal is to try to come up with a strategy that is effective in influencing the behaviour of the North Koreans at a time when the whole leadership situation is somewhat unclear."

The BBC's state department correspondent, Kim Ghattas, says that the North's sabre-rattling over the past few weeks is seen as an attempt to grab the attention of the Obama administration and improve its bargaining position when the talks eventually resume.

The North Koreans will be watching Mrs Clinton's every statement to determine their next move, our correspondent says.

Mrs Clinton arrived in Seoul from Indonesia - the world's most populous Muslim country - where she said the US was seeking a new kind of dialogue with the Muslim world.

In addition to talks with Indonesian leaders, Mrs Clinton appeared on a youth music TV show.

She joked about her poor singing abilities - but she also used her appearance to stress that Washington wants to address concerns over its policies in the Middle East and elsewhere.