In the UK, Prince Philip is said to have been left 'very shocked' but unhurt after crashing his car on one of the Queen Elizabeth's estates.
The 97-year-old was behind the wheel in Norfolk, when it collided with another car.
Images from the scene showed one of the cars on its side.
The prince and the driver of the other car were breathalysed - but both results were negative.
Questions are now being raised as to whether Prince Philip should still be driving at the age of 97.
There is no legal limit on driving ages in Britain.
The scene near the Sandringham Estate in Norfolk, where Prince Philip was involved in a road accident | Image: Sam Russell/PA Wire/PA Images
Edmund King, who's president of the AA in the UK, says there are protocols in place for elderly drivers.
"At the age 70 when you renew your licence, and then you have to renew it every three years with a medical declaration.
"We'd certainly like to see that you prove that you've had an eye test, so that your sight is actually good enough to drive"
Buckingham Palace said: "The Duke of Edinburgh was involved in a road traffic accident with another vehicle on Thursday afternoon.
"The Duke was not injured. The accident took place close to the Sandringham Estate. Local police attended the scene."
