TWO Americans freed from North Korea were reunited with family on Saturday after the surprise involvement of the top-ranking US intelligence official, who travelled to Pyongyang to secure their release.

Kenneth Bae and Matthew Todd Miller, who had been doing hard labour in North Korea, were accompanied by Director of National Intelligence James Clapper, who flew with them to Joint Base Lewis-McChord near Tacoma in Washington state.

Clapper oversees the CIA and some 15 other intelligence agencies, making his involvement in the men's release surprising. It was the first time a national intelligence director had been involved in such a high-profile diplomatic matter.

Bae thanked President Barack Obama and the North Korean government for his freedom, adding: "It's been an amazing two years, I learned a lot, I grew a lot, lost a lot of weight, in a good way, but I'm standing strong."

Bae was arrested in North Korea in November 2012 and sentenced to 15 years hard labour for crimes against the state.

Miller, who was tried on an espionage charge, had been in custody since April and was serving a six-year hard labour sentence.

Analysts could only guess at the reason for the releases, but North Korea has lately been on a diplomatic campaign to counter charges by the UN of widespread human rights abuses.