LONDON – Britain's Home Secretary Theresa May confirmed on Sunday that rioters who surrounded Prince Charles' car during violent student protests made physical contact with his wife Camilla.

A mob of demonstrators who joined in Thursday's protest against the hike in university tuition fees surrounded the car carrying the heir to the throne and the Duchess of Cornwall as they drove to a charity gala event.

A window on the Prince of Wales' side of the car was smashed, while the back of the car was spattered with paint hurled at it. The vehicle was also kicked.

May said she had been in touch with the royal household about the incident.

Asked by Sky News television about reports that Camilla had been jabbed by a protester through a window, May said: "I'm not sure about the term 'poked with a stick'. I understand there some contact made.

"This is an incident that needs to be looked at by the Metropolitan Police."

She also questioned the use of the Rolls-Royce Phantom VI car, which has big, high windows allowing royals and the public to see one another clearly.

"Royal protection is a matter that is reviewed regularly," May said.

"One of the issues that may very well be looked at is the whole question of the appropriate transport that's used."

The car was a gift to Queen Elizabeth II in her Silver Jubilee year of 1977, but there has been criticism that it is too distinctive and not secure enough for regular use.

May added: "Of course that's an incredibly regrettable incident that took place I think we should praise the Prince of Wales and the Duchess of Cornwall for their response.

"They carried on with the engagement that they were doing that evening so that they didn't let down the people who were expecting them.

"The Metropolitan Police are looking into the details of that incident to find out exactly how it arose and of course they will be wanting to learn the lessons from that."

The royal couple's Clarence House official residence said they were unharmed in the incident and were grateful for the police's efforts.