Formula One: Metal plate blamed for punctures to Vettel and Alonso's tyres at Spa

SPA-FRANCORCHAMPS, Belgium (REUTERS) - A metal plate shed by a car has been blamed for the alarming punctures suffered by Formula One world champion Sebastian Vettel and Ferrari's Fernando Alonso in Friday's Belgian Grand Prix practice.

Pirelli motorsport head Paul Hembery would not give precise details before teams had been informed but other sources said a metal plate had been found on the track at Turn 14, where both punctures occurred.

"There are certainly no tyre-related issues," Hembery told reporters on Saturday before final practice.

"We've seen no signs of fatigue and from our point of view, there's no reason to be concerned."

Drivers had expressed concern and asked race director Charlie Whiting on Friday for more information about the punctures.

A spate of blowouts at the British Grand Prix in Silverstone in June raised safety concerns that threw the sport into crisis before Pirelli changed the structure of the tyres last month to make them stronger.