Formula One drivers announced on Thursday they will withdraw from this weekend's German Grand Prix if the tire blowouts which marred Sunday's British race occur again.

During media conferences, drivers sounded confident that tire provider Pirelli had sorted out the problem by introducing new rubbers for the Nuerburgring race. However, following a meeting of the drivers' union, the tone hardened.

"The drivers of the Grand Prix Drivers' Association wish to express their deepest concerns about the events that took place at Silverstone," a statement said.