The Tube engineer, known only by his rap name Ahmz, travelled to Syria after hearing of an incident involving his cousin being tortured by government security forces.
Ahmz was a leading London-based protester against Assad’s regime, and has used YouTube videos to spread his message. He is believed to be the son of an opposition activist.
The 22-year-old, from Hornsey, said: “For people at home the revolution just seems to be something on the news after EastEnders. I couldn’t stand it any longer.”
He reportedly told The Times newspaper: “I’ve started to pray a bit as I might be dying soon. But I’m up for it. I’d be a wimp if I wasn’t.”
More than 8000 people have been killed by government forces since pro-democracy activists began attempts to oust Assad a year ago.