F1's tyre scandal could be set to deepen yet further, as a Spanish sports newspaper claims Pirelli - already under reprimand for 'test-gate' - blatantly broke the rules.
Marca correspondent Marco Canseco reports that, prior to the tyre-explosive British grand prix, F1's official supplier changed the construction of its 2013 tyre without the knowledge or the consent of the FIA or the teams.
"At worst, it jeopardised the lives of the drivers," Canseco said, referring to the spate of spectacular tyre failures at the British grand prix that have thrown the sport into crisis.
Marca said the tyres used at Silverstone had a completely new structure, with a layer of kevlar included in the internal steel-belt.
Earlier, teams including Lotus, Force India and Ferrari vetoed the introduction of the purely kevlar-belted tyres, due to the rule requiring unanimity for mid-season changes.
Canseco said he discovered Pirelli's breach when Sauber and McLaren sent team personnel out to the scene of Sunday's tyre explosions, only to discover kevlar shards among the debris.
Pirelli's Paul Hembery denies the charge.
"I can assure you that the tyres (at Silverstone) were the same construction as the ones used in Barcelona," he said.
Reacting to F1's new tyre crisis, the FIA has agreed to open up the forthcoming three-day young driver test at Silverstone to include the use of race drivers for tyre development.
"The test may also be extended by one day," read a statement issued by the Paris federation.
Mercedes, however, remains banned from the test, even though team director Toto Wolff expressed concerns about what the other teams will be allowed to do.
"If it is a pure tyre test, I'm all for it," he is quoted by Germany's Sport Bild.
The FIA also said it will seek the World Motor Sport Council's consent to allow Pirelli to introduce new specifications during the season without the need for unanimity.
"In the meantime," the governing body added, "the FIA has asked Pirelli for an assurance that there will be no repetition of the tyre problems at this weekend's German grand prix or at subsequent grands prix."
If that guarantee is not forthcoming, it is possible drivers will boycott the Nurburgring.
"I don't think that will happen," Bernie Ecclestone told the BBC.
But McLaren team boss Martin Whitmarsh insists: "There is that danger (of boycott), if it is not certain that it is safe.
"But this is not what we want for F1. We had these problems in Indianapolis (in 2005) and it was terrible for the sport.
"This is not the time to blame anyone," he is quoted by Auto Hebdo, "we need to work together and find a solution."
The Telegraph reports that Pirelli will "almost certainly" use its safer kevlar tyres this weekend.
"We would support this," Lotus boss Eric Boullier, who previously blocked the introduction of the kevlar tyres on sporting grounds, is quoted by AFP news agency.
"Safety is the primary concern," he insisted.
F1 chief executive Ecclestone confirmed: "They (Pirelli) can change them (the tyres).
"(FIA president) Jean (Todt) agreed with that and I told Pirelli."
Influential French sports daily L'Equipe headlined that the sport is "in tatters" after Silverstone, but the most damage has been to Pirelli's image.
"Fortunately they (Pirelli) don't make condoms," joked German tennis legend Boris Becker, according to Welt newspaper.
Ferrari's Stefano Domenicali thinks the Nurburgring will be a "less stressful" circuit for tyres than high-speed Silverstone.
Red Bull could have cost Rosberg Silverstone win - report
It was Red Bull who alerted the FIA to a rules breach that could have cost Nico Rosberg victory at Silverstone last Sunday.
We have reported that, in the wake of the bitter 'test-gate' scandal, the tension between world champions Red Bull and Mercedes remains palpable.
So just after Rosberg's champagne-soaked celebrations on Sunday, it emerged that the German driver and his team were summoned by the stewards to explain his alleged failure to slow for yellow flags.
The officials decided simply to reprimand Rosberg.
Germany's Bild newspaper reports on Tuesday that it was Red Bull who alerted the FIA to Rosberg's breach, which if punished with a time penalty could have cost him the win.
Dr Helmut Marko defended Red Bull's actions.
"We did not attack Mercedes, but only pointed out that Rosberg was too fast under a yellow flag.
"If it had been us (committing the breach), the other teams would also immediately tell the FIA. It's a totally normal thing," the Austrian insisted.
Van der Garde plays down Kovalainen rumours
Giedo van der Garde has dismissed rumours he could be set to lose his 2013 Caterham seat to former team driver Heikki Kovalainen.
We reported at the weekend that it was possible Finn Kovalainen, back in the paddock at Silverstone, could now return to Caterham's race lineup, at Dutchman van der Garde's expense.
"Nothing has been agreed, so do not try to guess," Kovalainen told Finland's Turun Sanomat newspaper at Silverstone.
But 28-year-old van der Garde dismissed the speculation, in conversation with the Dutch newspaper De Telegraaf.
"There are always rumours," he said.
"I know where they are coming from, but I also know that I have a watertight contract for the rest of this season."
De Telegraaf acknowledged, however, that in the wake of van der Garde's dismal race in Canada, where he was penalised by the FIA for collisions, Caterham team owner Tony Fernandes was in contact with Kovalainen.