WASHINGTON/SEOUL (REUTERS) - A representative for former United States (US) President Jimmy Carter denied reports on Monday that he was planning to visit North Korea soon to try to win the release of an American citizen being held in the reclusive nation.

South Korea's Yonhap news agency reported that Carter, 88, would be visiting soon to urge the release of Kenneth Bae, who was sentenced in May for committing crimes against North Korea.

Ms Deanna Congileo, a spokeswoman at the Carter Centre in Atlanta, said that is not the case. "President Carter has no immediate plans to visit North Korea," she said in an emailed statement.

Representatives of the Elders, an international group of former statesmen and women that includes Carter, also denied the South Korean report.

"The Elders have no plans to visit North Korea," said a spokesman for group, Ms Jennifer Woodside, adding that the last time they had visited North Korea was in April 2011.

Yonhap quoted a source in Washington as saying Mr Carter had made contact with the North to arrange for the visit and that he was likely to make the trip in a personal capacity to secure Bae's release.

"The issue of Kenneth Bae who has been held in the North for nine months is becoming a burden for the United States," Yonhap quoted the diplomatic source as saying. "Even if Carter's visit materializes, it will be focused on the issue of Kenneth Bae's release more than anything else."

Bae's family has said his health is deteriorating and has asked for help in securing his release.

The White House said if Mr Carter made such a trip, it would be in his personal capacity.

"We have seen footage of Mr Bae and it was clear that his health was deteriorating, which is of grave concern," State Department spokesman Jen Psaki told a briefing.

"We continue to urge North Korean authorities to grant Mr Bae amnesty and immediate release," she said.

Asked whether Secretary of State John Kerry would support Mr Carter's effort if he decided to go, Ms Psaki said Mr Carter had not decided to go.

DIPLOMATIC STANDOFF

Bae, who is in his mid-40s, was sentenced to 15 years hard labor by North Korea's Supreme Court after being detained in November as he led a tour group through the northern region of the country.

North Korea accused Bae of participating in activities designed to overthrow the government, by infiltrating at least 250 students into the country.

Bae has acknowledged being a missionary and has said he conducted religious services in the North.

He said he had been moved by his faith to preach in North Korea, ranked for years as the most hostile nation to Christianity by Open Doors International, a Christian advocacy and aid group.

Bae's arrest and conviction came amid a tense diplomatic standoff between North Korea and the US surrounding Pyongyang's missile and nuclear tests and its claim that Washington was plotting to attack the country.

In two months of daily verbal assaults earlier this year prompted by annual drills by the US and South Korean militaries, Pyongyang threatened to attack the two allies using its nuclear weapons.

Pyongyang has a history of trying to use American captives as a bargaining chip to drag Washington into talks, but the Obama administration has been reluctant to respond.

Mr Carter has made trips to the North on diplomatic missions and in 2010 helped win the release of another American, Mr Aijalon Mahli Gomes, a Boston native who had been sentenced to eight years hard labour for illegally entering the country.

Former President Bill Clinton flew to North Korea in 2009 and secured the release of two American women who had been sentenced to 12 years for illegally entering the country.