Rebel forces and armed civilians are rounding up thousands of black Libyans and migrants from sub-Sahara Africa, acccusing them of fighting for ousted strongman Moammar Gadhafi and holding them in makeshift jails across the capital.

Virtually all of the detainees say they are innocent migrant workers, and in most cases there is no evidence that they are lying. But that is not stopping the rebels from placing the men in facilities like the Gate of the Sea sports club, where about 200 detainees – all black – clustered on a soccer field this week, bunching against a high wall to avoid the scorching sun…

In an office nearby where sports trophies still lined the shelves, Ibrahim al-Rais, a 60-year-old fisherman, acted as prison director. A bag held wallets and IDs taken from the captives. Another was stuffed with cell phones, which occasionally rang.

He acknowledged that many of the detainees were likely innocent migrant workers stranded in the country but he insisted that a “big percentage” were mercenaries.