The United States on Friday fully implemented travel restrictions against six Muslim-majority countries, North Korea and Venezuela, South Korea's Yonhap news agency reported.

The restrictions were announced in a proclamation signed by President Donald Trump in September but faced legal appeals. The Supreme Court ruled Monday to allow the order to be enforced while the legal proceedings continue.

"The Department began implementing the full Proclamation at the opening of business (local time) at US embassies and consulates overseas today, Friday, Dec 8, 2017," the State Department said in a statement.

National security is the top priority in US visa operations, it said, and the embassies and consulates will fully implement the proclamation to "protect the American people."

"All countries share the responsibility to prevent terrorist attacks, transnational crime, and immigration fraud," it said.

The eight nations, including Chad, Iran, Libya, Somalia, Syria, and Yemen, are accused of failing to comply with US requirements designed to ensure travellers do not pose a national security or public safety threat.

The order calls for enhancing vetting capabilities at the US diplomatic missions.

The restrictions can be lifted if the targeted countries work with the US government to ensure the safety of Americans, according to the State Department.

Suspending entry of North Koreans is largely symbolic, as the communist regime imposes strict controls on its citizens' travels and few are thought to come to the US.

Tensions between Washington and Pyongyang have escalated for months over the regime's testing of nuclear weapons and ballistic missiles aimed at the US mainland.

- Bernama