The United States on Friday temporarily banned the entry of lawful permanent residents ​who have been in the Democratic Republic of ‌Congo (DRC), Uganda or South Sudan in the previous 21 days, citing concerns over Ebola.

US citizens, nationals and green card holders had ​been exempt from a 30-day Ebola ban, ​but the US Centres for Disease Control and Prevention (CDC) said on Friday that ⁠extending the ban to green card holders was necessary ​to stop the virus from entering the country.

“Applying this ​authority to lawful permanent residents for a limited period of time provides a balance between protecting public health and managing emergency ​response resources,” the CDC ​said in a statement.

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The World Health Organisation on Friday raised to “very ‌high” ⁠the risk of the rare Bundibugyo strain of Ebola turning into a national outbreak in the DRC and has declared the outbreak there and in Uganda an emergency ​of international ​concern.

The CDC first ⁠issued the order on Monday under Title 42 of the US public health law, ​which allows federal health authorities to prohibit ​migrants from ⁠entering the country to prevent the spread of contagious diseases.

Green card holders have historically been shielded from US ⁠entry ​restrictions. The CDC’s COVID-era Title 42 ​order did not apply to them, nor did President Donald Trump’s ​various travel bans.

A rare strain of Ebola has prompted the World Health Organisation to declare a public health emergency of international concern.

Most of the cases have occurred in the DRC, with at least 131 fatalities associated ⁠with the outbreak. There have been ​516 suspected cases and 33 confirmed cases in Congo, according to ​a daily bulletin published by health authorities, and two confirmed cases in neighbouring Uganda.

The head of the World Health ​Organisation expressed deep concern at the speed ‌and scale of the Ebola outbreak, as the number of cases rises.