Having drawn widespread criticism for comments attributed to him over the legality of the Mercedes upgrade, Christian Horner has gone on record as saying he believes the car is fully "legal".

No sooner had Mercedes revealed the W13's radical upgrade than the German media reported that Horner had questioned its legality, prompting fears, even before the season has begun, that the car will be protested.

While Horner and Red Bull both quickly denied that he had made the claim, it was subsequently pointed out that anything he might have said was not "official".

Speaking on the record, Horner now says that he believes there is no question as to the upgrade's legality.

"I think it's interesting, it's very innovative what Mercedes has come up with," he told reporters at the official press conference. "It's quite a different concept to the concept that we pursued and some of the others have.

"It shows the creativity, even within constrictive regulations in Formula One, that very different solutions are coming out," he continued. "Whether it's the right route or whatever, only time will tell.

"What we see in F1, is there tends to be convergence over a period of time on design philosophies," he added. "But what's so good about this sport is you get a clean sheet of paper, you get ten different interpretations... Mercedes has come up with an extreme one that's a different interpretation.

"Whether we think it's illegal or not, yes, absolutely, it looks like it ticks all the boxes." he replied, when asked about the claim he is alleged to have made days earlier.

"The comments that have been quoted certainly weren't made," he insisted." I think the car is obviously innovative, it's an interesting solution. I think as far as we're concerned, the Mercedes car looks like it complies with the regulations. It's just a different interpretation, a different solution.

"There's not really anything that defines the spirit of the regulations, it either complies or it doesn't," he added. "It's not really for us to judge. The FIA has the access to all of the drawings, a design like that surely would've been submitted in advance.

"It's an interesting concept, it's a radical concept. Is it quick or not? Only time will tell, but in terms of its compliance, that's very much an FIA matter."

Asked if he though Mercedes had taken the right route, the winning route, he replied: "Obviously visually it's quite a departure from the concepts that certainly we've taken and quite a few other teams have taken. That doesn't mean to say it's naturally better or worse. It's just a different interpretation, and of course there's compromises that have been made with their layout to accommodate that.

"It's impossible to draw any conclusions other than obviously that it looks very different. For me the car that looks the most settled on the circuit at the moment is the Ferrari. I think they've had a very strong test so far, both in Barcelona and in Bahrain.

"So I would say they've looked extremely competitive whenever they've been on track. You have to remember that these cars are still very immature, the rate of development will be fast and intense. I expect that to change, and Mercedes are going to be a huge factor in this championship, I've no doubt."

Talking of Ferrari, while Christian Horner might be in no doubt about the legality of the W13's upgrade, Mattia Binotto has called into question the mirrors on the Mercedes, which the Italian team believes could provide an aerodynamic advantage.

"I am somehow surprised," he told reporters. "I find them quite surprising, and it is something that we are not expecting.

"I think in the spirit of that, it is something that I think for the future needs to be addressed," he continued. "Already in the past we always argue the mirrors should not have any aero purpose, they should be there just to look behind.

"I think that the way that they have designed their car, certainly there is a significant aero purpose in the mirrors itself. I think it is something that we need to stop for the future, no doubt, because the risk is that we will come in the future, that all the teams will start designing mirrors, that will look like spaceships. I don't think that's what we are looking for as an F1.

"I'm not arguing against the idea," he insisted. "I think they found a solution that is interesting, but I think in the spirit of what we intend to do, certainly for the future, it is something that we need to discuss.

"No doubt it's a great car," he said of the W13. "Good concept, quite different to the one we got. I think what is interesting is the layout and the sidepods again.

"On the legality overall, I don't think that we can have any doubt. It has gone through a process and the FIA is certainly the one which is responsible for policing and making sure it's fully legal. And I don't think Mercedes is doing something illegal as well."

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