Mr Fulton (far left) and his wife worked with pastors in The Gambia
The friend of a Scottish missionary being held in a high security prison in The Gambia has called on the country's president to release him.
David Fulton, 60, from Troon in Ayrshire and his wife Fiona, 46, from Torquay in Devon, were arrested on 29 November and accused of sedition.
Jim Rae, from Motherwell, said he was concerned about his friend's health as he understood he was not eating.
The Foreign Office said British consular staff were providing support.
Mr Fulton works as a chaplain in the mainly Muslim country's army, and first moved to The Gambia 12 years ago.
The prosecution has accused the couple of writing letters to individuals and groups abroad to "bring into hatred or contempt, to excite disaffection" against the Gambian president, the Reuters news agency reported.
The couple have pleaded not guilty and were granted bail of £125,000 ($181,600), which they have reportedly yet to find.
Mr Rae, a water engineer who met Mr and Mrs Fulton in The Gambia eight years ago, said he did not know if Mr Fulton was on hunger strike or too ill eat.
"The stories that are coming back from the prison is that Davey is not eating and apparently he is not well, he is a bit sick," he said.
"His body is failing, according to the contact, and that worries me - his physical condition as well as the kind of stress he must be under.
"I don't know whether he's going on hunger strike or whether this is just a question of his body can't eat at the moment because of the pressure he is under."
Mr Rae said his friend has been under a lot of stress, because of domestic difficulties and said his judgement in recent times could have been better.
He made an emotional appeal to President Yahya Jammeh to show clemency.
He said: "I hope you can see your way to try and understand he has put himself under tremendous amount of pressure and his domestic circumstances have caused him a tremendous amount of pressure.
Mr and Mrs Fulton were arrested and accused of sedition.
"He has served the Gambia well in the past, but in the last couple of years maybe he has lost his way. But I would ask you to take everything into consideration, send the guy home."
Mr Fulton, a former army major, is said to be held at a high security jail outside the capital, Banjul.
Mrs Fulton is being held with the couple's two-year-old adopted daughter at a police station in Banjul.
Mrs Fulton is understood to spend her time looking after terminally ill people and visiting women in their homes and in hospital.
The Gambia is one of Africa's smallest countries and has been ruled by President Jammeh since 1994, when he seized power.
President Jammeh's government has been criticised by international rights groups for its attitude to civil liberties, especially freedom of the press.
The country has a secular constitution, but its population is 90% Muslim.
A Foreign Office spokesman said: "Two British nationals have been arrested in The Gambia and Foreign Office consular staff have been in touch with the couple and are providing consular assistance."