Theo said he was sodomised with a truncheon, as well as racially abused, spat at and beaten around his genitals.
He has undergone emergency surgery for severe anal injuries, and has been declared unfit for work for 60 days. He remains in hospital, where he spoke to his lawyer.
He said the police operation quickly turned violent and he was set upon by four officers. He struggled to make sure he was in the view of CCTV cameras, and asked the officers why they were doing this to him.
He said one officer proceeded to pull his trousers down and rape him with a truncheon.
"I fell on to my stomach, I had no strength left," he said.
He was then sprayed with tear gas around the head and in the mouth and hit over the head, he said.
