Mercedes team principal Ross Brawn continues to insist that there is no case for the Brackley-based squad to answer regarding its involvement in a controversial tyre test following the Spanish Grand Prix.

Speaking to BBC Sport ahead of the Canadian round this weekend, Brawn revealed further details of the test, including explaining why his team did not openly announce its involvement, and why he feels that it did nothing wrong, despite in-season testing - particularly with a current car - being in contravention of F1's sporting regulations.

There was no mention of the alleged green light from the FIA's Charlie Whiting to run the W04, but Brawn remains confident that Mercedes will be exonerated when it appears in front of a tribunal assembled by the governing body.

"It was a Pirelli test, on the Wednesday to Friday after the [Spanish] race," he confirmed, "It couldn't be held any closer to the weekend because people were packing up. On the Tuesday, there were still motorhomes begin disassembled, garages being taken apart, and there we were, in our full regalia with the trucks and the Pirelli trucks and everything. There was no secrecy involved; it was privacy."

Using the same reasoning to answer questions about why Nico Rosberg and Lewis Hamilton wore anonymous plain helmets for the 1000km test, Brawn maintained that he did not want to draw unwarranted attention to the session, even if there was no attempt to hide it from rivals within the F1 paddock.

"It was a Pirelli test, we don't believe we had an obligation to inform other teams - if Pirelli wanted to inform other teams, that's up to them," Brawn argued, "We're comfortable it was a Pirelli test requested by Pirelli. It's for Pirelli to decide what they want to do with it.

"You don't go testing in Barcelona for three days and expect people not to know about it - my conscience is clear," he claimed, "The reason for the drivers' helmets is it was a Pirelli test, they organised the security, they organised all the arrangements.

"We didn't want to bring attention to the drivers, we didn't want to have to put security there, we didn't want to have to put minders [there]. The easiest way for us was to not bring attention to what drivers were in the car, [but] only for those reasons. We have always been very open about the drivers, [but] the drivers are irrelevant - there's nothing in the sporting regulations, nothing in the arrangements for these tests, that controls which drivers are in the car."

It is the use of the W04, rather than Rosberg and Hamilton, that has raised eyebrows up and down the pit-lane, with several teams firmly believing that Mercedes - which was struggling to contain tyre wear with its 2013 car - will have gained a significant advantage from the test. Rosberg duly followed the test with victory in Monaco, but the acid test may well be this weekend's race in Montreal, which will tax the rubber much more than the streets of the Principality.

Pirelli has already decided not to use its 'development' tyre beyond free practice in Canada, ostensibly to give the other ten teams a chance to try it out before it is introduced for all sessions, including the race, at Silverstone in three weeks' time. Brawn, however, maintains that his drivers and engineers did not know which tyres they were working with at any time.

"[The drivers] had some awareness of the tyres, but that's the awareness you have to give a driver if tyre testing," he explained, "If you want to be effective in testing, you have to give the driver some guidance of what you are looking for, [but] it wasn't: 'this is the tyre we're using at the next race'."

Pirelli insists that, while the tyre due for introduction in Canada had been added to the test batch at late notice, and on safety grounds, the basis of the session was to develop rubber for 2014.