Jailed Greenpeace video journalist Kieron Bryan said he fears losing years of his life away from family, friends and his girlfriend.
Bryan was arrested by Russian special forces on 19 September aboard the Greenpeace ship Arctic Sunrise, alongside 29 activists, on a filming job for the environmental pressure group.
In a letter to the Sunday Times, Bryan said: "My greatest fear is being kept from my family, my friends and my girlfriend for any great length of time.
"In many ways I'm lucky I don't have children who depend on me, but the fear of losing years of my life and the opportunity to perhaps start a family is terrifying."
The Russian authorities reduced the charges against the 30 activists last week from piracy to hooliganism, but they could still face up to seven years in prison.
This Sat in London: a silent protest on behalf of videojournalist Kieron Bryan, imprisoned for doing his job: http://t.co/Z522LGc79S
— Oxford NUJ (@OxfordNUJ) October 28, 2013
Bryan described his treatment in the detention centre as “ludicrous’. He said: "I spend 23 hours a day in here with nothing but the occasional book and my thoughts. We are granted an hour a day for exercise which is held in a shed about 30 metres from my cell. If I'm lucky I might get to shout a quick hello to an English speaker."
Last week an Early Day Motion was tabled against Bryan's prosecution, which has now been signed by 24 MPs.
Almost 1400 journalists have signed a petition to free Bryan. A silent protest will be held outside the Russian Embassy on Saturday 2nd November between noon and 2pm.