The other 7 countries -- in the Middle East -- were already on the exclusion list. (Representational)

Washington on Monday revoked visa-free entry rights to the United States for foreigners who have visited North Korea in the past eight years, potentially dealing a new blow to the isolated country's nascent tourist industry.

The US allows citizens of 38 countries -- including South Korea, Japan and France -- to enter for up to 90 days without a visa under a waiver programme.

But visitors who have travelled to eight countries including North Korea since March 1, 2011 are "no longer eligible", details posted Monday on the US Customs and Border Protection website showed, and they will have to apply for tourist or business visas.

The other seven countries -- most of them in the Middle East -- were already on the exclusion list.

The change will affect tens of thousands of people from visa waiver countries who have gone to the North as tourists or for other purposes in recent years.

It will also put a damper on South Korean President Moon Jae-in's hopes of promoting cross-border tourism projects for his citizens to visit their nuclear-armed neighbour.

South Korean media put the spotlight on top business leaders including Samsung Electronics vice chairman Lee Jae-yong who were part of Moon's delegation to Pyongyang for a summit with North Korean leader Kim Jong Un in September.

A Samsung spokesperson declined to comment.

US citizens have been banned from visiting North Korea since 2017, a measure introduced after an American student detained in Pyongyang was released in a coma and died a few days later.