Former US president Jimmy Carter is planning to visit the Democratic People's Republic of Korea (DPRK) soon to try to win the release of a US citizen held for committing crimes against the state, Seoul-based Yonhap News Agency reported on Monday.

Jimmy Carter, former US president

Carter has made contact with the DPRK to arrange for the visit, and he is likely to make the trip in a personal capacity to secure the release of US citizen Kenneth Bae, a source in Washington was quoted as saying by Yonhap.

The diplomatic source was quoted as saying that the issue "is becoming a burden for the United States.

"Even if Carter's visit materializes, it will be focused on the issue of Kenneth Bae's release more than anything else."

The DPRK's Supreme Court sentenced Bae in May to 15 years hard labor after he was detained in November leading a tour group through the northern region of the country.

Pyongyang said Bae was participating in activities designed to overthrow the government by infiltrating at least 250 students into the country.

Bae has acknowledged to being a missionary and has said he had conducted services in the DPRK.