The United States is moving to add more countries to its travel ban list, US President Donald Trump has said, without giving details.

Mr Trump said on Wednesday (local time) the changes would be announced soon.

A source familiar with the draft proposal said the tentative list of nations included Belarus, Eritrea, Kyrgyzstan, Myanmar, Nigeria, Sudan and Tanzania.

The move could dampen relations between the US and the countries affected under the expanded ban.

Nigeria, for example, Africa's largest economy and most populous country, is a US anti-terrorism partner and has a large diaspora residing in the United States.

A senior Trump administration official said countries that failed to comply with security requirements, including biometrics, information-sharing and counter-terrorism measures, faced the risk of limitations on US immigration.

Officials from the White House, Department of Homeland Security and the State Department have declined to comment on the planned expansion of the travel ban.

In 2018, the US Supreme Court handed Mr Trump one of the biggest victories of his presidency at the time, by upholding his travel ban targeting several Muslim-majority countries and rejecting the idea it represented unconstitutional religious discrimination.

Under the current version of the ban, citizens of Iran, Libya, North Korea, Somalia, Syria and Yemen, as well as some Venezuelan officials and their relatives are blocked from obtaining a large range of US immigrant and non-immigrant visas.

Chad was previously covered under the ban but was removed in April 2018.

Reuters