Britain said on Tuesday it was seeking the release of an elderly British man facing 350 lashes after being caught with homemade wine in Saudi Arabia, a sentence which his family said could kill him.
Karl Andree, 74, was jailed for 12 months in August last year but remains in prison awaiting further punishment for breaking strict Saudi laws prohibiting alcohol after police found the wine in his car, his family said.
"There were two sentences. The custodial sentence which finished in August and then there's the lashing sentence ... which I assume he's been kept in there because that hasn't been dealt with yet," his son Simon Andree told BBC radio.
"We have no idea what's going to happen in respect of that.
"I'm not criticising Saudi because it's their law, it's their way of life. My father has served his time, he regrets what's happened, he just wishes to come home now."
He said his father, who had worked for oil companies in the kingdom for some 25 years, was in poor health, had suffered cancer three times, and also had asthma.
"He's an old frail man and I fear this lashing sentence is potentially a death sentence for him," Simon Andree said. "That's our biggest concern, which is why we are trying to raise the case now to get him out."
Britain's Foreign Office, which warns on its website that there are severe penalties for possessing alcohol in Saudi Arabia, said embassy staff in Riyadh were checking Andree's health regularly.
"Ministers and senior officials have raised Mr Andree's case with the Saudi Government and we are actively seeking his release as soon as possible," a spokesman said.
No one was available to give an immediate response from the Saudi Embassy in London.
The Andree case comes just over a week after British Prime Minister David Cameron urged Britain's Middle East ally not to go ahead with the execution of a Shi'ite Muslim sentenced to death over his role in anti-government protests when activists said he was just 17.