An investigation by the British newspaper Sunday Telegraph has revealed hundreds of African migrants locked up in Saudi Arabia's coronavirus detention facilities under terrible conditions.

The investigation, published on Sunday, revealed photos taken by migrants on their mobile phones showing dozens of emaciated men lying on the floor in multiple rows in small rooms with barred windows.

"It's hell in here. We are treated like animals and beaten every day," Abebe, an Ethiopian who has been held at one of the centres for more than four months, told The Sunday Telegraph.

Other migrants said they were beaten using electric cords, with guards hurling racial abuse at them.

At least one teenager took his own life by hanging himself, the newspaper reported.

"Photos emerging from detention centres in southern Saudi Arabia show that authorities there are subjecting Horn of Africa migrants to squalid, crowded, and dehumanising conditions with no regard for their safety or dignity," Adam Coogle, deputy director of Human Rights Watch in the Middle East, was quoted as saying by the newspaper.

"The squalid detention centres in southern Saudi Arabia fall well short of international standards. For a wealthy country like Saudi Arabia, there's no excuse for holding migrants in such deplorable conditions"

The newspaper was able to geolocate two of the centres - one is in Al Shumaisi, near the holy city of Mecca, while the other is in Jazan, a port town near Yemen.

There are believed to be others housing thousands of Ethiopians.

In March, the government of Saudi Arabia deported nearly 3,000 Ethiopian migrant workers as it struggled to deal with the coronavirus outbreak.

A further 200,000 migrants were also slated for deportation, but instead were rounded up from various cities within the oil-rich kingdom and have been left in squalid conditions in detention facilities.

Others are African refugees from war-torn Yemen.