Geneva - Sauber have blamed the Interlagos track for the rear wing failures that forced the Swiss-based Formula One team to withdraw from Sunday's Brazilian Grand Prix on safety grounds.
Sauber's findings came as the sport's ruling body on Wednesday summoned the Brazilian organisers to a meeting in Paris next week to discuss "incidents" which occurred in qualifying.
Qualifying was stopped three times on Saturday when advertising hoardings broke loose and fell on the circuit, one of them hitting the Prost driven by Frenchman Jean Alesi.
In separate incidents several of the teams suffered rear wing problems.
They included both Saubers, the team withdrawing on Saturday after Finland's Mika Salo crashed at high speed.
Sauber said they had carried out a full investigation and concluded that both wing failures arose from unusual circumstances due to the bumpy surface of the track.
The team said the failure on Salo's car was on the lower plane of the rear wing while on Brazilian Pedro Diniz's car it was on the upper plane.
"The track at Interlagos had been resurfaced but was even bumpier than before on the main straight on which cars exceed 170 mph," the team added in a statement.
"These very severe bumps resulted in both cars undergoing impact loads that were considerably in excess of the cycle predicted during the design of the cars, which itself incorporated a significant safety margin."
The team said it was satisfied that the "surface characteristics were directly responsible for the failures."
Pointed the finger
"We are confident now that running the cars at Silverstone on Wednesday and Thursday does not present any risk and that such failures will not recur."
Former world champion Jackie Stewart also pointed the finger of blame at the track on Sunday.
The International Automobile Federation (FIA) said in a statement that the Brazilian organisers would be heard at a meeting of the World Motor Sport Council on April 6.
"Having examined the reports of officials with regard to the incidents which occurred during the qualifying practice...the FIA has summoned the organisers of this event," it said.
A FIA court of three judges is also due to sit in Paris on Monday to hear McLaren's appeal against David Coulthard's disqualification from Sunday's race after his car failed a post-race inspection.
Coulthard finished runner-up to Ferrari's Michael Schumacher, winner of the first two races of the season.
Falling ad boards
Organisers of the Brazilian Grand Prix face possible fines - and even the loss of the race - after advertising boards fell on the track during qualifying for last Sunday's race.
FIA, the world governing body of auto racing, on Wednesday summoned event organisers to appear at a hearing on April 6 before the World Motor Sports Council.
"Being called in like this is usually not to give them (organizers) flowers," FIA spokesman Francesco Longanesi said.
Longanesi said it was possible Brazil could lose the race because of the incident, "or face some kind of fine or sanction, or maybe nothing if there's an explanation for what happened."
"The FIA has the power to do this (take away the race)" Longanesi added.
On Saturday in Sao Paulo, three advertising billboards fell onto the track, forcing red flags in the qualifying sessions. One of the boards, crashing to the surface from 10 metres above the track, nicked the right front wing of Jean Alesi's Prost Peugeot.
He was uninjured.
"We just don't want to see this brushed under the carpet," Longanesi said. - Reuters-Sapa-AP