The last two Americans serving lengthy prison sentences in North Korea have arrived in the US after the Asia pacific nation freed them following a secret mission by the US intelligence chief James Clapper.

Kenneth Bae and Matthew Miller arrived around 0500 GMT on Sunday at Joint Base Lewis-McChord in Washington State.

Bae disembarked the plane with a suitcase, then smiled as he hugged and embraced family and friends, followed by Miller, who was also greeted by family members.

Bae and Miller had both been sentenced to several years of hard labour for crimes against North Korea.

"Thank you all for not forgetting me, and for not forgetting the people of North Korea," Bae said during a press conference following his arrival.

US President Barack Obama said on Saturday he was "grateful" for North Korea's decision to release the two Americans.

"I think it's a wonderful day for them and their families," he said in Washington.

"I appreciate Director (of National Intelligence James) Clapper doing a great job on what was obviously a challenging mission".

Charges of espionage

The US State Department said that they had been held by the Pyongyang authorities for two years and seven months, respectively.

In its statement, the department said: "The safety and welfare of US citizens abroad is the Department of State's highest priority, and the US has long called on DPRK [North Korea] authorities to release these individuals on humanitarian grounds.

"We join their families and friends in welcoming them home."

The statement also thanked the government of Sweden for its efforts to help secure the freedom of Bae and Miller.

"The Department of State reiterates our strong recommendation against all travel by US citizens to the DPRK," it said.

Miller, who is from California, was serving a six-year jail term on charges of espionage, after he allegedly ripped up his tourist visa at Pyongyang's airport in April and demanded asylum.

Bae, who is from Washington state, is a Korean-American missionary with health problems. He was serving a 15-year sentence for alleged anti-government activities.

The two were the last Americans held by North Korea following the release last month of Chris Fowle. Fowle was released by Pyongyang on October 21.

Source: Agencies