The Trump administration is set to ban US citizens from travelling to North Korea following the death of university student Otto Warmbier who fell into a coma in a North Korean prison.

US officials said that Secretary of State Rex Tillerson had decided to implement a “geographical travel restriction” for North Korea, which would make the use of US passports to enter the country illegal.

They said the restriction would go into effect 30 days after a notice is published in the Federal Register but it was not immediately clear when that would be. There was no announcement in Friday’s editions of the government publication.

Rex Tillerson speaking at a press conferenceIt is claimed Rex Tillerson has decided on the ban (Efrem Lukatsky/AP)

Two tour operators that organise group trips to North Korea said they had already been informed of the decision.

Under US law, the secretary of state has the authority to designate passports as restricted for travel to countries with which the United States is at war, when armed hostilities are in progress, or when there is imminent danger to the public health or physical security of US travellers.

Geographic travel restrictions are rare but have been used by numerous administrations in the past for countries where it has been determined to be unsafe.

Since 1967, such bans have been imposed intermittently on countries such as Algeria, Iraq, Lebanon, Libya, Sudan, Cuba and North Vietnam.

In this case, the administration had been considering the step since Mr Warmbier died after being medically evacuated in a coma from North Korea last month. He suffered a severe neurological injury from an unknown cause while in custody.

Relatives said they were told the 22-year-old University of Virginia student had been in a coma since shortly after he was sentenced to 15 years of hard labor in North Korea in March 2016. He had been accused of stealing a propaganda poster while on a tour of the country.

The United States, South Korea and others often accuse North Korea of using foreign detainees to wrest diplomatic concessions. At least three other Americans remain in custody in the North.