Bill Clinton arrived in North Korea today on a surprise visit to seek the release of two American journalists serving 12 years for "grave crimes", in the highest profile visit to the country by an American for nearly a decade.

The highly unusual trip comes amid increased tensions between Washington and Pyongyang over the stalled aid-for-disarmament talks and the latter's recent nuclear test and missile launches.

The former US president was greeted by the North's chief nuclear negotiator, Kim Kye-gwan, and a high-ranking parliamentary official after landing in an unmarked jet this morning. A young girl presented him with a bouquet.

US officials have confirmed Clinton will negotiate for the freedom of Laura Ling and Euna Lee, who were arrested in March on the border with China.

The journalists were detained while on a reporting trip for California-based Current TV – co-founded by Al Gore, Clinton's former vice-president. They were sentenced in June to 12 years of hard labour for entering the country illegally and engaging in "hostile acts".

North Korea and the US do not have diplomatic relations, but Washington is believed to be working behind the scenes to negotiate their release. Hillary Clinton, the US secretary of state, has said "everyone is very sorry" about the incident and urged Pyongyang to grant them amnesty.

Kim Yong-hyun, a professor at Seoul's Dongguk University, said Bill Clinton's visit could serve two purposes: securing the women's release and improving ties between the two countries.

"I think it's not just about journalists. It will serve as a turning point in the US-North Korea relations," he said.

It is not yet clear whether Clinton will meet the North's "Dear Leader", Kim Jong-il.

Pyongyang has increased tensions in recent months, but many analysts suggested its primary goal was to push the Obama administration into engaging with it. Last week it said it was open to talks on its nuclear programme – an apparent call for direct discussions with the US.

Washington has said it could talk bilaterally with the North, but only on the sidelines of six party talks – also involving China, Japan, South Korea and Russia – which Pyongyang has denounced.

Clinton is the second former US president to visit North Korea. Jimmy Carter visited in 1994, when Clinton was in office, and met the then-leader Kim Il-sung, the late father of the current leader. The visit came amid escalating nuclear tensions and led to a breakthrough deal months later.

Six years later, Clinton's secretary of state, Madeleine Albright, visited Pyongyang for talks with Kim Jong-il. But after George Bush took office he declared the North to be part of an "axis of evil" with Iran and Iraq.

Asked about Clinton's visit, South Korean foreign ministry officials said any announcement would come from Washington or Pyongyang.

There was no immediate response from Clinton's New York foundation, and Gore's spokeswoman, Kalee Kreider, said she could not comment.

A senior US official travelling to Africa with Hillary Clinton told reporters : "While the mission is in progress, we will have no comment ... Our interest is the successful completion of the mission and the safe return of the journalists."

North Korea is also holding a South Korean worker accused of insulting the North's political system and the four-man crew of a South Korean fishing boat that strayed north of a maritime border last week after experiencing navigational problems.