The Vatican has been left red-faced after it emerged that a car bearing its diplomatic plates had been stopped in France with four kilograms of cocaine on board.

The car - which also contained 200g of cannabis - belonged to 91-year-old Argentinian cardinal Jorge Mejia, emeritus librarian at the Holy See, who retired in 2003 and who is currently bedridden.

Pope Francis has visited Jorge Mejia in hospital as news of the drugs find broke. Credit:Jung Yeon-Je/Getty Images

Pope Francis, a fellow Argentinian, visited Mejia, who was confined to a hospital in Rome after a heart attack, just two days after being elected.

French radio reported that the cardinal's private secretary entrusted the vehicle to two Italian men to take it for its annual check-up.