They have now urged Liz Truss, the Foreign Secretary, to designate Mohammed Al Shaibani, the director of the Ruler’s Court in Dubai, for sanctions under the UK’s global human rights sanctions regulations and the global anti-corruption sanctions regulations.

This would include freezing any financial assets he holds in the UK and barring him entry to Britain.

Mr Shaibani, one of the Emirate of Dubai’s most powerful figures and chairman of DIB, denies the Briton was held on his orders.

In their letter to Ms Truss, the peers and MPs state: “These two British citizens languish in a Dubai jail as hostages until they die of illness or old age, with no prospect of ever being reunited with their families.

“A failure by our Government to act will confirm to corporate raiders in autocratic states that they can trash the rights of British citizens with impunity in pursuit of financial gain. This will make life even more hazardous for British business people on whose success in foreign markets this country’s future prosperity depends.”

Mr Cornelius is suffering from tuberculosis caught from an infected inmate, and his family fear he may not live to see the end of his sentence.

His wife Heather – on whose behalf barristers Rhys Davies and Ben Keith also submitted a request to the Foreign Secretary on Thursday for sanctions to be imposed – said: “The British Government have looked on indifferently, unwilling to intervene or to help him in any way.”

In a speech to the House of Lords in June last year Lord Clement Jones said: “Ryan served his 10 years in full, denied the statutory 25 per cent reduction for good behaviour.