The American Christian missionary who spent two years in a North Korean labour camp before being freed over the weekend "bears no ill will" towards the communist country, his sister says.

Kenneth Bae was released from imprisonment on Saturday morning along with fellow American citizen Matthew Miller, and both have since arrived back in the US.

Appearing briefly in front of reports after his arrival at a Washington state military base on Saturday, Bae said: "I learned a lot."

The release of the two men came on the back of a mission by the US's director of national intelligence James Clapper.

Bae's sister, Terri Chung, spoke to reporters outside her church in Seattle and said that he was in good condition.

After arriving back in Seattle, Bae's first meal was pizza but preparations are underway for a "big celebration" over the Thanksgiving holiday, she said.

Bae was a tour operator in North Korea at the time of his arrest in 2012.  He was later sentenced to 15 years of hard labour on charges of attempting to overthrow the North Korean government.

Chung said that in spite of her brother's ordeal, he "still has a tremendous heart for North Korea" and "bears no ill will" towards the country, NBC News reports.

The return of Bae and Miller to the US follows the release of another American citizen, Jeffrey Fowle, from detention in North Korea last month. He was arrested in May after allegedly leaving a Bible in a hotel room.

He told NBC News following his release that he had wanted to help underground Christians in North Korea.

"It was a risk I was willing to assume at that time," he said. "I was so motivated by the stories of the underground Christians that I felt compelled to help them."

He told CBS News: "I wouldn't do it again, but at the time I felt like I had to do it. I was doing what I thought God wanted me to do."

Miller had been held in North Korea since April and was sentenced to six years in prison for "hostile acts". He has not spoken to the media since his return to the US.