Protesters at the British Grand Prix are being urged not to invade the track on race day.
Northamptonshire Police says it has received intelligence that individuals may attempt to interrupt the Formula 1 event at Silverstone on Sunday.
Appealing directly to the protesters, Chief Inspector Tom Thompson said: "I strongly urge you to not put yourselves, the drivers, as well as the many marshals, volunteers and members of the public, at risk."
With racers travelling at speeds of more than 140mph, the event commander described the plans as "reckless" - and stressed "going on a live racetrack is extremely dangerous".
He added: "Protesting is of course everyone's human right in this country and we are more than happy to speak with you to help you facilitate a peaceful protest at the circuit, we just please ask that you do not create a situation that puts lives in danger."
The force has confirmed that "extra resources will be in place throughout the race weekend should anyone ignore these warnings and try to disrupt the event".
Ch Insp Thompson urged members of the public to be "extra vigilant" and approach an officer if something doesn't look right - and said the police would rather have a "well-meaning report that turns out to be nothing, than not receive one at all".
He said: "We are very experienced in the policing of this event having done so over a number of years but let me make this clear - this doesn't make us complacent.
"The security measures we have put in place are as stringent as ever and anyone thinking of taking advantage of the race weekend to commit a crime will be caught."
Protesters have been told they can speak to Northamptonshire Police ahead of race day by calling 101 and using Op Pitlane as the reference.