SEOUL – Former U.S. President Bill Clinton made a surprise visit to North Korea on Tuesday to try to win the release of two jailed American journalists, and met the country's reclusive leader Kim Jong-il.

Some analysts said the visit, which U.S. officials insisted was a private one, could mark the isolated state's return to talks over nuclear weapons.

North Korea's KCNA news agency also said that Clinton, who had dinner with Kim, passed on a verbal message from U.S. President Barack Obama but gave no details. Washington said that no such message had been relayed.

Kim Jong Il expressed thanks for this, KCNA said of the message. He welcomed Clinton's visit to the DPRK (North Korea) and had an exhaustive conversation with him. There was a wide-ranging exchange of views on the matters of common concern.

The White House also appeared to play down speculation about a possible breakthrough in U.S.-North Korean relations by characterizing Clinton's trip as private.

While this solely private mission to secure the release of two Americans is on the ground, we will have no comment. We do not want to jeopardize the success of former President Clinton's mission, White House spokesman Robert Gibbs said in a statement.

Clinton's trip followed months of military provocations by the impoverished North, which has turned its back on negotiations with regional powers, including the United States and China, to convince it to give up ambitions to build an atomic arsenal.

JAILED FOR SLANDER

North Korea's chief nuclear negotiator, Kim Kye-gwan, was among those greeting Clinton -- whose administration was reported to have considered bombing the North's Yongbyon atomic plant in the early 1990s.

Television footage showed a dark-suited, stern-faced Clinton in a vigorous hand shake with one official. He looked less serious when a girl dressed in traditional costume presented him with flowers before he was led to a black limousine.

As soon as he arrives, he will be entering negotiations with the North for the release of the female journalists, South Korea's Yonhap news agency quoted a source as saying.

The two journalists -- Euna Lee and Laura Ling, of U.S. media outlet Current TV co-founded by Clinton's vice president Al Gore -- were arrested on the North Korea-China border in March, accused of illegal entry and being bent on slander.

A North Korean court sentenced them each last month to 12 years hard labor for what it called grave crimes.

Many analysts predicted Pyongyang would use the journalists as leverage to wring concessions from Washington, which led pressure for U.N. sanctions on the North for a May nuclear test.

FOUNDATION FOR BETTER TIES?

In Washington, Republican Sen. Lindsey Graham of South Carolina told U.S. television it was not clear whether Clinton had been authorised to discuss policy issues.

It would be nice if it's the foundation for a better relationship, Graham, a prominent member of the Senate Armed Services Committee, told NBC's Today Show.

If he could sit down with the North Koreans and convey a message from the administration and the Congress to be more reasonable when it comes to verifying their nuclear program and getting away from the development of nuclear weapons, it'd be a good thing.

Yun Duk-min of the Institute of Foreign Affairs and National Security in Seoul said the visit held out the possibility of a dramatic turnaround by North Korea that could lead to a new phase of negotiations.

But trade data suggests the North may be resorting more to barter trade to make it more difficult for the international community to pressure Pyongyang through sanctions.

It is the second time a former U.S. president has headed to the communist state to try to defuse a crisis. Former president Jimmy Carter flew there in 1994 when tensions were running high, again over the North's nuclear weapons program.

A senior official traveling with U.S. Secretary of State Hillary Clinton said there would be no comment during the mission. Our interest here is the successful completion of the mission and the safe return of the journalists.

Hillary Clinton, flying to Kenya for a trade conference, enraged Pyongyang's leaders last month by likening them to unruly children seeking attention, adding that they did not deserve it.

One analyst said that was exactly what the former president's visit was doing -- rewarding bad behavior.

Clinton's arrival coincides with mounting speculation over succession in Asia's only communist dynasty. Several reports suggest that an increasingly frail-looking Kim Jong-il, 67, has settled on his third son to take over.

It's just what they (North Korea's leaders) need, said B.R. Myers, an expert on the North's state ideology at the South's Dongseo University.

It allows the government to show to a domestic audience, facing deepening poverty, that the nuclear weapons program is making the outside world take it more seriously and the visit will be certain to be portrayed as tribute by the United States.

And it will confirm to North Korea that bad behavior will be rewarded further, Myers said. It sends all the wrong signals. (Additional reporting by Yoo Choonsik in Seoul, Lucy Hornby in Beijing, Sue Pleming en route to Kenya and David Morgan in Washington; Writing by Jonathan Thatcher; Editing by Jeremy Laurence)