Neither Jenson Button or Mark Webber believe that Nico Rosberg's Monaco Grand Prix victory was the result of the allegedly illegal test it conducted with Pirelli in the wake of the previous round in Spain.

Rosberg led the blue riband event from start to finish after converting pole position into his second career victory, but the success was soured by reports that he and team-mate Lewis Hamilton took part in a three-day tyre test at the Circuit de Catalunya immediately after struggling to convert a front row lock-out into decent results in the Spanish Grand Prix.

The matter has now been referred to the FIA after rival teams protested the test on the grounds of clarity. Both Red Bull and Ferrari said they had no prior knowledge of the test, and claimed that the rulebook said that any such work should have been open to all. The F1 sporting regulations, meanwhile, state that there can be no testing in-season, unless on the grounds of safety, and running cannot be carried out using a contemporary car. Mercedes, which provided its 2013 contender, and Pirelli, which insists that the test focused largely on tyres for next season, insist that the session was above board and had been approved by the governing body.

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While possible sanctions remain unclear, two drivers beaten by Rosberg on Sunday insist that it was unlikely Mercedes gained any Monaco advantage from the test.

"It's a fair question, [and] I think we were probably a little bit surprised that it happened, but I don't think it probably had a huge bearing on today's result," Red Bull's Mark Webber admitted, "I think their car was always going to perform pretty well round here, to be fair.

"You can't unlearn what went on at the test, obviously, so we need to see how it came about and whether it's within the rules or not. I'm sure Mercedes thought it was okay, so that's why they did it. Time will tell, but I don't think it affected the result."

Jenson Button, meanwhile, says he expects Mercedes to escape serious punishment.

"They have done a great job and, even without that tyre test, I think they would have won the [Monaco] race," the McLaren driver was quoted by Britain's Guardian newspaper, "I think the teams that protested are more surprised that it happened.

"I can't see the result changing. I don't know what they can do, if anything at all - maybe a slapped wrist. I think the teams that protested just wanted clarification because we'd all love to do 1000km to understand [the tyres] a bit more."