The US has said it would revoke all visas held by South Sudanese passport holders over that country's failure to accept the return of repatriated citizens.

South Sudan had failed to respect the principle that every country must accept the return of its citizens in a timely manner when another country, including the US, seeks to remove them, US Secretary of State Marco Rubio said in a statement on Saturday.  

"Effective immediately, the United States Department of State is taking actions to revoke all visas held by South Sudanese passport holders and prevent further issuance to prevent entry into the United States by South Sudanese passport holders," Rubio said.

"We will be prepared to review these actions when South Sudan is in full cooperation," he said.

First such measure

It was the first such measure singling out all passport holders from a particular country since Donald Trump returned to the White House on January 20, having campaigned on an anti-immigration platform.

The world's newest country and also one of the poorest, South Sudan is currently prey to tensions between political leaders.

Some observers fear a renewal of the civil war that killed 400,000 people between 2013 and 2018.