North Korea released American college student Otto Warmbier: Rex Tillerson

North Korea has released Otto Warmbier, an American college student who was serving a 15-year prison term with hard labor for alleged anti-state acts, Secretary of State Rex Tillerson said Tuesday.

The US announcement that came as former NBA player Dennis Rodman was paying a return visit to Pyongyang.

"At the direction of the President, the Department of State has secured the release of Otto Warmbier from North Korea," Tillerson said in a statement. "Mr. Warmbier is en route to the US where he will be reunited with his family."

The Washington Post, citing Warmbier's parents, reported that he had been medically evacuated from North Korea in a coma, and was due to arrive home in Cincinnati on Tuesday evening. The report said he had been a coma for more than a year, since shortly after his last public appearance at his trial in Pyongyang in March 2016.

The Associated Press could not immediately confirm that information. Warmbier's family did not respond to calls seeking comment.

The statement by Tillerson, which he later read Tuesday morning at a congressional hearing, offered no other details and made no mention of Rodman's visit. Tillerson said the department would have no further comment on Warmbier and his condition, citing privacy concerns.

But he noted that the State Department is continuing "to have discussions" with North Korea about the release of other three American citizens who are jailed there.

A North Korean foreign ministry official said Warmbier was released and left the country Tuesday morning.

The photo taken on February 29, 2016 and released by North Korea's official Korean Central News Agency (KCNA) on March 1, 2016 shows American student Otto Frederick Warmbier (R), who was arrested for committing hostile acts against North Korea, speaking at a press conference in Pyongyang. (Photo by AFP)

The official, who spoke to the AP on condition of anonymity because no formal statement had been released, said he could not provide further details.

It was not immediately clear if Rodman's visit to North Korea was purely coincidental with Warmbier's release. Rodman has traveled to the isolated nation four times previously and is one of few people to have met both North Korean leader Kim Jong Un and President Donald Trump. Speaking to reporters in Beijing before his arrival in Pyongyang on Tuesday, he said that the issue of several Americans detained by North Korea is "not my purpose right now."

In March 2016, North Korea's highest court sentenced Warmbier to 15 years in prison with hard labor for subversion as he tearfully confessed that he had tried to steal a propaganda banner.

Warmbier, 22, a University of Virginia undergraduate, was convicted and sentenced in a one-hour trial in North Korea's Supreme Court.

The US government condemned the sentence and accused North Korea of using such American detainees as political pawns.