North Korean media have shown images of Mr Clinton and President Kim
Former US President Bill Clinton has met North Korean leader Kim Jong-il during an unannounced visit to the country, state media have reported.
Mr Clinton is in Pyongyang to discuss the fate of jailed US journalists Laura Ling and Euna Lee.
He is the highest-profile American to visit since his secretary of state, Madeleine Albright, in 2000.
US media are reporting that Mr Clinton has met the journalists and hopes are high for their release.
Analysts say Mr Clinton may also be trying to ease the deadlock over the North's nuclear ambitions.
The Korean Central News Agency (KCNA) said that Mr Clinton had "courteously" conveyed a verbal message from US President Barack Obama, although the White House said Mr Clinton had not carried a message from Mr Obama.
Bill Clinton was given flowers on his arrival in Pyongyang
The ABC News network says government sources in Washington have said they hope the former president and the two women will leave North Korea soon.
Washington made no announcement of Mr Clinton's trip prior to his arrival, but in a later statement stressed it was a private visit.
"While this solely private mission to secure the release of two Americans is on the ground, we will have no comment," White House spokesman Robert Gibbs told reporters.
John Sudworth BBC News, Seoul
According to North Korea's official state media, Kim Jong-il hosted a dinner for the former US president, before the two men exchanged what is described as a "broad range of opinion".
Face-to-face time with the North Korean leader is extremely rare for Western politicians, and granting the opportunity to Bill Clinton could be a sign that he is going to be given what he came for - the release of two American journalists.
Mr Clinton is also reported to have delivered a verbal message from President Obama, but the White House is remaining very tight lipped. It says the case of the journalists must remain separate from wider political issues.
"We do not want to jeopardise the success of former President Clinton's mission."
However, North Korea analyst Prof Hazel Smith, of the UK's Cranfield University, told the BBC that Mr Clinton would have the full backing of the White House.
"This is not a private mission, although it being billed as such," she said. "There is no way that [former] President Clinton, married to Secretary of State Hillary Clinton... would be taking this step without the full support of the US administration."
The last visit to North Korea by a former American president - Jimmy Carter in 1994 - led to an important step forward in relations between the two countries, and Mr Clinton may be hoping his trip will have the same effect.
But some analysts question the wisdom of such a high-profile visit so soon after North Korea conducted a string of nuclear and missile tests in defiance of the UN Security Council - saying it may be seen by Pyongyang as a reward for bad behaviour.
Mr Clinton landed in Pyongyang in an unmarked plane and was greeted at the airport by North Korean officials, including chief nuclear negotiator Kim Kye-gwan and Yang Hyong-sop, vice president of parliament.
US JOURNALISTS JAILED
17 March: Euna Lee, left, and Laura Ling seized by North Korean border guards while reporting for California-based Current TV
8 June: Sentenced to 12 years in jail for "hostile acts" and illegal entry into North Korea
16 June: North Korea says journalists have "admitted and accepted" their guilt
10 July: US Secretary of State Hillary Clinton appeals for an amnesty for the two
4 August: Former US President Bill Clinton arrives in Pyongyang to discuss the journalists' fate
As he stepped down from the plane, a little girl came forward to present him with a bouquet of flowers.
No official itinerary for the visit has been announced.
Analysts say that Kim Jong-il is eager to improve relations with Washington as he prepares to name a successor.
Mr Kim is thought to have suffered a stroke a year ago, and also has chronic diabetes and heart disease. Analysts say his third son is already being lined up to take over power one day.
Journalists Laura Ling and Euna Lee were found guilty of entering North Korea illegally across the Chinese border in March, and sentenced to 12 years' hard labour.
They were arrested by North Korean guards while filming a video about refugees for California-based internet broadcaster Current TV.
According to KCNA, the two reporters have admitted entering the country illegally.
But the women's families have always said that Lee, 36, and Ling, 32, had no intention of crossing into North Korea.
This is not the first time a senior US statesman has gone to North Korea to negotiate for the release of American citizens.
In 1994, then-congressman Bill Richardson - now governor of New Mexico - helped negotiate the release of Bobby Hall, one of two pilots of a US army helicopter shot down after straying into North Korea.
Two years later, he negotiated the release of Evan Hunziker, who was detained on suspicion of spying after swimming the Yalu river border.
Critics say Mr Clinton's trip will be exploited for maximum propaganda value by Pyongyang.
However, although his arrival was covered by North Korea's evening television news, it was not until after apparently more newsworthy items, such as the improving quality standards at a biscuit factory, says our correspondent in Seoul, John Sudworth.
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