Formula One's drivers are demanding guarantees about the safety of the latest Pirelli tyres ahead of the Belgian Grand Prix.
The move comes just two races after a boycott of the race in Germany was threatened by the drivers in the wake of the dangerous blowouts that overshadowed the British Grand Prix at the end of June.
Fresh concerns, however, have been raised in the wake of punctures suffered by Sebastian Vettel and Fernando Alonso yesterday during practice for tomorrow's race at the high-speed Spa-Francorchamps circuit.
Pirelli motorsport director Paul Hembery met with FIA race director Charlie Whiting to discuss the situation and it is understood Whiting is to review the matter ahead of final practice today once Pirelli has completed its findings.
But Red Bull Racing's Mark Webber said: "We need answers and 'debris' is not the answer."
Given what occurred in practice, Alonso said: "I don't think it's a similar problem to what we saw in Silverstone, maybe more of a random set of circumstances, but all the same, it needs careful analysis."
As for Vettel, he said: "We don't know what happened when I got the puncture in P2. We lost the rear right, very suddenly, so we need to have a look.
"Pirelli is working on finding out why it happened. Other than that, it was a positive day."
Hembery earlier dismissed fears of a repeat of what occurred over the Silverstone weekend, but again his reputation and that of Pirelli are on the line.
By his own admission, however, Hembery said: "It is a worry for the sport because we have to go out and find what it is."
But asked specifically whether there could be a repeat of the horror show at Silverstone, he added: "It is completely different."
With photographs of both the offending tyres in his hands, Hembery pointed to two puncture holes in Alonso's rubber.
As for Vettel, there was a long scar on a part of the surface before it materialised into a puncture further round, suggesting to Hembery the circuit itself had played an intrinsic part in the failures.
"It looks on the Red Bull as though something has been rubbing on the surface and then has just cut through it," explained Hembery.
"It rubs through and comes up to a point where it just digs in.
"On the Ferrari there are two quite clear holes through the top of the tread. There's not a lot we can do about that.
"So we have to go and look at the track and see what is between turns 13 [Fagnes] and 15 [Stavelot].
"We have seen a lot of signs on other tyres, small surface cuts, so there is clearly something. I cannot tell you what it is, but it is from external sources."
Vettel's incident did not stop him from topping the timesheet with a lap of one minute 49.331 secs ahead of Red Bull Racing teammate Webber, with the Lotus of Romain Grosjean completing the top three.
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