Red Bull has admitted that a device to alter its front bib height does exist but insists it cannot be used while the car is assembled.
Speculation about a team exploiting a way of lifting and lowering the height of its T-tray erupted on the eve of the United States Grand Prix when the FIA revealed that it was imposing a clampdown on the matter.
The governing body said that following concerns expressed by teams about potential exploitation by a rival of parc ferme rules to adjust its ride height between qualifying and the race, new procedures were being introduced from the Austin weekend.
One way that this could be done would be through the fitting of seals on devices that can be adjusted to alter the ride height of the front bib to ensure they cannot be moved.
As teams gathered in Austin for this weekend's F1 race, it became clear that the focus of the matter revolved around the Red Bull team.
Sources suggest that competitors had been alerted at the Singapore Grand Prix to speculation about the Milton Keynes-based squad having a way to adjust its front bib height through a change of settings on a component in an area accessible from the cockpit.
This was found through Red Bull having to publish design details of that element on FIA servers as part of the regulations revolving around open-source parts.
It has been suggested that this device had a range of settings that could be adjusted by a mechanic to help alter the height of the ride height.
Performing this action would be allowed throughout practice, so the component itself is not outside the regulations, but it would be illegal if changes were made under parc ferme conditions that begin from qualifying and last until the race.
It is understood that discussions took place between teams concerned about the matter and the FIA over the Marina Bay circuit weekend.
Following those talks, it is understood that the governing body held talks with Red Bull before the race there to ensure that it was not doing anything untoward.
Speaking this week, the FIA said that there was no evidence that Red Bull had actually adjusted the device while the car was under parc ferme conditions.
However, from now on, monitoring of this aspect of the car would be ramped up to ensure it was an area where no one could work outside the regulations.
Red Bull has denied doing anything untoward and insists that the device that has emerged as central to this matter cannot be altered once the car is assembled.
A senior team representative said: "Yes it exists although it is inaccessible once the car is fully assembled and ready to run.
"In the numerous correspondence we have with the FIA, this part came up and we have agreed a plan going forward."
The controversy over the ride height adjustment comes ahead of what will be an intense battle between Red Bull and McLaren for the F1 title.
Both teams are keeping a close watch over what their rival is up to, with McLaren having recently been on the receiving end of a probe about the flexibility of its rear wing.
With the way it which its upper element helped rotate back to open up the slot gap earning it the 'mini-DRS' tag, it agreed to make modifications following discussions with the FIA.
Watch: Why Red Bull's Bib "Trick" has Sparked Controversy - F1 US GP Media Day Reaction
