The pugilist, who had represented England six times in major competitions, including in a fight against Nigeria, was detained at the Tinsley House Immigration Centre at Gatwick Airport in West Sussex on Nov 29, according to Daily Mail UK.
The 29-year-old, who was taken to the UK illegally by an uncle when he was 14, was the 2012 ABA light-middleweight champion.
The boxer, popularly known as Kelvin and married to an English woman, initially took up boxing to survive, but he soon became famous as a result of his talents.
His application to remain in the UK has been rejected by the Home Office, which also declared his marriage to the Briton void.
Fawaz said: “I’m allowed to box for England but I’m not allowed to stay in England.
“I’ve spent over half of my life here – I went to school here, I lived here, I’ve boxed for England six times and never lost.
“I am a national champion – in 2014, I even boxed for England against Nigeria, the country they want to deport me to.”
He claims his mother is dead and he has no idea where his father is.