SEOUL (REUTERS) - A United States (US) missionary imprisoned in North Korea for more than a year appeared in front of journalists on Monday, in prison clothes and under guard, asking Washington to help him get home, foreign media there reported.

Mr Kenneth Bae, a 45-year-old ethnic Korean, was arrested as he led a tour group in North Korea in 2012 and sentenced to 15 years of hard labour on charges of state subversion.

Mr Bae met "a limited number of media outlets" in the North Korean capital Pyongyang and expressed hope of the United States securing his release, Japan's Kyodo news agency reported.

Mr Bae's son Jonathan urged Washington to respond to the statement.

His father's words "obviously mean that Washington has not done enough. We need to send someone over and bring him home.

That's what it's going to take. He needs to come home," Mr Bae told Reuters by phone.

Awakened to learn of his father's televised statement, the younger Bae described his emotions as "mixed," with relief that Mr Bae was alive.

In Washington, an administration official said the US had offered to send US special envoy to North Korea Robert King to Pyongyang to secure Bae's release.

"We hope this decision by DPRK authorities to allow Kenneth Bae to meet with reporters signals their willingness to release him," the official said, speaking on condition of anonymity. "We have offered to send Ambassador King to Pyongyang to secure Mr Bae's release. We have asked the North Koreans this, and await their early response," the official added.

Separately, State Department spokesman Marie Harf said the US was concerned about Bae's health. "We continue to urge the DPRK authorities to grant Bae amnesty and immediate release," she said in a statement.

It was not immediately clear why the North Korean authorities had allowed the event at Pyongyang Friendship Hospital, Mr Bae's second media appearance since his arrest.

North Korea's state KCNA news agency reported Mr Bae himself had asked to hold the press conference.

Footage of the appearance released by Kyodo showed Mr Bae in a drab grey prison uniform and baseball cap.

He appeared to be in reasonable health before he was escorted out by uniformed North Korean officials.

Mr Bae's appeal came days after reclusive North Korea demanded that South Korea and the United States halt annual military drills due in February and March - but also offered the South a truce in hostilities, provocations and mutual criticism.

"MISINFORMATION"

North Korea's Supreme Court had said Mr Bae used his tourism business to form groups aimed at overthrowing the government.

KCNA reported that at the press conference, Mr Bae acknowledged he had broken North Korean laws and said he wanted to clarify"misinformation" surrounding his incarceration that had"enraged" the North.

"I, availing myself of this opportunity, call on the US government, media and my family to stop linking any smear campaign against the DPRK and false materials with me, making my situation worse," Mr Bae was quoted by KCNA as saying in comments in line with other media reports.

DPRK is short for the North's official name, the Democratic People's Republic of Korea.

"I hope that I will be pardoned by the DPRK and go back to my family. I request the US government, media and my family to pay deep concern and make all efforts to this end," he added, according to KCNA.

An attempt to secure Mr Bae's release by a US emissary was called off by Pyongyang in August and there has been no official contact between the US and North Korea since then.

Mr Bae is believed to be in ill health and led missionary groups into North Korea, according to speeches he made that were posted on the Internet.

On one of his trips, Mr Bae recalled singing hymns together with his mission tourists at a beach surrounded by North Koreans.

An American veteran of the Korean War, Mr Merrill Newman, who was captured in 2013 by the North and freed after seven weeks, made a confession of his "offences", but later said his statement had been made under duress.