The FIA is considering banning the use of DRS in the tunnel at this weekend's Monaco Grand Prix on the back of continued safety complaints from drivers, AUTOSPORT can reveal.
A majority of drivers have expressed reservations about the possible dangers they could face in Monaco by having to use the DRS - especially through the tricky right-hander in the tunnel.
And although the FIA saw no grounds to ban DRS entirely - with the overtaking zone to be laid down on the start-finish straight - some consideration is now being given to the tunnel situation for practice and qualifying, when DRS can normally be used without restriction.
Drivers have continued to voice their fears about the situation, and AUTOSPORT understands that Formula 1 race director Charlie Whiting is giving serious thought to imposing a ban on using DRS through the tunnel.
A decision on the matter will be made in the next 24 hours - so teams and drivers are well aware of the situation before first practice in Monaco begins on Thursday.
Speaking last weekend, Whiting said the FIA believed there were no safety problems with having DRS available in Monaco.
"I've spoken to the drivers a few times about it and it was quite clear that the majority of them did not want to use it in Monaco," he explained during a media briefing. "However, there is no evidence to support the theory that it is unsafe in Monaco.
"Obviously, we are not waiting for an accident to happen, but there is simply no evidence to support the theory that it is going to be dangerous. So as it has been introduced as an overtaking aid, it would be somewhat perverse not to allow it in the place where you need overtaking the most.
"So there is no reason not to use it in Monaco as far as we can see. That is the long and the short of it. As far as we are concerned it's a device that's open to anyone to use legally at any race. That is what it is there for."
When asked if the FIA could change its mind over that decision if there were accidents or complaints, Whiting said: "Yes, we can. If we think there is a problem, then we can stop its use. If there was something that we felt was wrong and dangerous, then we would stop it. But we can do that with any part of the car, so it's not unusual."
One of the biggest issues that the drivers are unhappy about with the DRS through the tunnel is that the wing setting is either fully open or fully closed - which means there is a big step difference between downforce levels if they use the device.
The tunnel is fast enough and crucial enough to a lap time that drivers may feel that they have to run through the tricky corner with the DRS open - even though they are unsure about grip levels.