(CNN) Forgetting those behind bars as coronavirus cases continue to surge in Europe and the US could be "potentially catastrophic," UN High Commissioner for Human Rights Michelle Bachelet says.

"In many countries, detention facilities are overcrowded, in some cases dangerously so. People are often held in unhygienic conditions and health services are inadequate or even nonexistent. Physical distancing and self-isolation in such conditions are practically impossible," Bachelet said in a statement.

Governments across the world should take urgent action to slow the spread of the virus within facilities including jails and prisons, immigrant detention centers, residential care homes, psychiatric hospitals and orphanages.

"It is vital that governments should address the situation of detained people in their crisis planning to protect detainees, staff, visitors and of course wider society," she said.