North Korea frees detained US citizens Kenneth Bae and Matthew Miller

The US men had been sentenced to years of hard labour

Kenneth Bae and Matthew Miller while in custody in North Korea (Reuters; AP)

The North Korean government has freed the last two US citizens it was holding in detention, according to US officials.

Three weeks after another American had been released by North Korea, Kenneth Bae and Matthew Todd Miller have been put on their way back to the US, accompanied by director of national intelligence James Clapper.

In September, having destroyed his tourist visa in the hopes of fulfilling a "wild ambition" to experience North Korea's prisons, the 24-year-old Mr Miller was sentenced to six years' hard labour for what was described as "hostile acts."

Mr Bae, a Christian missionary and tour operator, was arrested in November 2012 over accusations that he was using his tourism business to plot against the government. In May 2013 he was sentenced to 15 years in a labour camp.

The United States had frequently called for their release for humanitarian reasons, especially since Bae was said to have health problems.

"We are grateful to Director of National Intelligence Clapper, who engaged on behalf of the United States in discussions with DPRK authorities about the release of two citizens," the U.S. State Department said in a statement after the men were freed.

"We also want to thank our international partners, especially our Protecting Power, the government of Sweden, for their tireless efforts to help secure the freedom of Mr. Bae and Mr. Miller."

Sweden serves as a diplomatic intermediary for the United States in North Korea, as Washington has no diplomatic ties with Pyongyang.

In late October North Korea freed Jeffrey Fowle, 56, a street repair worker from Miamisburg, Ohio, who had been arrested in May for leaving a Bible in a sailor's club in the North Korean city of Chongjin, where he was traveling as a tourist.

In September, the authoritarian North Korean government allowed Bae, Miller and Fowle to be interviewed by CNN and the Associated Press. The men said they were being treated humanely and appealed to the U.S. government to push for their release.

The interview was seen as a sign that North Korea was looking for a way to open dialogue with Washington

A US official told the Associated Press that nothing was given in return for the American citizens, and that though the US appreciates the move, it will continue to regard North Korea unfavourably until it sorts out its human rights and commits to denuclearisation.

Additional reporting from agencies