The migrants at Tariq Al-Siqa centre are provided with shoes and kit to play a five-a-side tournament in the detention centre's concrete courtyard, with metal-framed mini goals and hand-painted touch-lines. They are cheered on by fellow detainees.
Some have been arrested as they attempted to reach Italy by boat, others rounded up as irregular migrants as they try to scratch a living from day labour in Tripoli and other Libyan cities. Most are from West Africa.
The detention centres, some of which have official status, are notorious for poor conditions. Abuse against migrants in the centres and in informal shelters run by smugglers has been widely documented by the United Nations and non-governmental organisations.
"The initiative is to alleviate the migrants' psychological and social suffering," said Husni Abu Ayyana, an official at Tariq Al Siqa.
Libya is the most common departure point for migrants crossing to Europe by sea, with more than 600,000 traversing the central Mediterranean route since 2014.
Departures have dropped sharply since July as more migrants have been blocked from leaving or intercepted by the Libyan coastguard, meaning that numbers in detention centres have swelled.
(Reporting by Ahmed Elumami; Editing by Aidan Lewis and Emelia Sithole-Matarise)
