North Korean officials claimed Warmbier fell into a coma in March last year due to "botulism" food poisoning.

"He was arrested, tried on spurious charges and evidently subjected to horrendous mistreatment by North Korean authorities.

This was outrageous behavior even by the standards of one of the world's most vicious and isolated regimes. It should not go unpunished," the paper said in an editorial.

It also said that what happened to Warmbier is the result of "North Korea's odious practice of seizing Americans to use as political pawns." President Donald Trump should make it a priority to win the release of three other Americans detained in the North, the editorial said.

"The United States should also move quickly to step up sanctions on the regime of Kim Jong-un, which has been racing to develop missiles that can reach the United States with a nuclear warhead," it said.

American visitors have often been detained in North Korea on charges of anti-state and other unspecified crimes. The widespread views are that the communist nation has used the detentions as bargaining chips in its negotiations with Washington.

Kenneth Bae, a Korean-American missionary, served two years of detention in the North before being released in November 2014 when then-US Director of National Intelligence James Clapper made a secret trip to Pyongyang to win his release and that of another US detainee. (Yonhap)