The US is to ban its citizens from travelling to North Korea.
Koryo Tours and Young Pioneer Tours, who both operate there, said the ban would be announced on 27 July to come into effect 30 days later.
They were informed by the Swedish embassy, which conducts US affairs in the country.
US officials have confirmed the ban to US media and linked it to the death of jailed American student Otto Warmbier, but given no details on date or scope.
Mr Warmbier travelled to North Korea with Young Pioneer Tours. He was arrested in 2016 for trying to steal a propaganda sign and sentenced to 15 years in prison. He was returned to the US in a coma in June and died a week later.
Koryo Tours and Young Pioneer Tours both revealed on Friday that they had been told of the upcoming ban by the Swedish embassy, which acts for the US as Washington has no diplomatic relations with Pyongyang.
Rowan Beard, of Young Pioneer Tours, told the BBC the embassy was urging all US nationals to depart immediately.
He said the embassy was trying to check on the number of US tourists left in the country.