Amidst increasing suspicion from rival teams, McLaren has agreed to modify its controversial rear wing.

While there has been talk for some time of the wing flexing, TV coverage during last week's race in Baku cast even further doubt on its legality.

Footage from race-winner Oscar Piastri's McLaren appeared to show the upper element of the rear wing rotate at speed on the straights, giving the appearance of opening up the slot gap, thereby reducing drag and increasing top speed. In the aftermath of the race the phenomenon was referred to as a 'mini-DRS'.

The wing was discussed by the drivers during Thursday's press conference with Charles Leclerc admitting that it was "controversial to say the least" and Sergio Perez insisting that it was a "massive benefit."

"I am very happy that we're doing a very good job," insisted Lando Norris in reaction to the claims, "everything has been tested, everything is legal, so we are doing what we can.

"That is what Formula 1 is for," he added, "exploring everything within the rules. We've cleared all the tests and the FIA is happy so I am proud what the team is doing."

In a statement on Thursday, the FIA said that it was "closely monitoring the flexibility of bodywork on all cars" and reserved the right to request teams to make modifications at any point during the season".

"However, if a team successfully passes all deflection tests and adheres to the regulations and technical directives, they are deemed to be in full compliance, and no further action will be taken," said the sport's governing body, as it revealed that it was reviewing data and any additional evidence that emerged from the Baku event whilst considering any mitigating measures for future implementation.

"This is part of the standard process when scrutineering technical legality, and the FIA retains the authority to introduce regulatory changes during the season if required," it declared.

In reaction McLaren has now agreed to modify the wing, though it insists it is already fully legal.

"Whilst our Baku rear wing complies with the regulations and passes all FIA deflection tests, McLaren have proactively offered to make some minor adjustments to the wing following our conversations with the FIA.

"We would also expect the FIA to have similar conversations with other teams in relation to the compliance of their rear wings."

"I think it's more than borderline," insisted Fred Vasseur at today's press conference. "We all saw the videos and pictures of this, and it's a bit frustrating when, if you remember the situation in Monza, we had five cars in two hundredths of a second, and you move from P1 or P2 to P5 or P6 for two hundredths of a second.

"In Baku we had ten laps in a row when we arrived side-by-side at Turn 1, so you can imagine that we have a bit of frustration."

As Helmut Marko called on the FIA to now turn its attention to the front wings on the McLaren (and Mercedes), Vasseur said: I think there is a kind of confusion between what happened with the front wing and the rear wing.

"The front wing we all agree that it could be a grey area because on the the first paragraph of the TD (technical directive) is saying you can't design part of the car with the intention of the deformation. Intention is difficult to manage.

"The rear wing story is completely different because in the article you also have a maximum deflection, and this is black or white. It's not grey, or dark grey, or light grey. It's black. And for me it's clear."