Formula One CEO Stefano Domenicali has criticised "irresponsible" protesters who invaded the Silverstone track during the opening lap of the British Grand Prix.
A huge first-corner crash involving Zhou Guanyu, George Russell and Alex Albon saw the race red-flagged, with protestors breaking onto the circuit at the Wellington Straight and sitting down on the track as cars headed for the pits.
The protesters were dragged away by marshals as drivers sped by, with Northamptonshire Police later confirming seven arrests had been made before the race resumed after over a 50-minute delay.
"Totally irresponsible," Domenicali told Sky Sports. "People can protest something by voice, but running the risk on a track, jeopardising and having the really serious stuff for the drivers and themselves is totally stupid.
"This is not acceptable, you can protest whatever you want, there is freedom to speak, but this is really ridiculous."
Domenicali later added in a statement: "Everyone has the right to speak out on issues, but no one has the right to put lives in danger. The actions of a small group of people today were completely irresponsible and dangerous.
"We thank the police for their great work and we shouldn't be complacent about the risk this posed to the safety of the drivers, marshals, fans and the individuals themselves."
An F1 spokesman told Sky Sports: "We can confirm that after the red flag several people attempted to enter the track. These people were immediately removed and the matter is now being dealt with by the local authorities."
Northamptonshire Police released a statement on social media after the resumption of the race to confirm that arrests had been made.
The statement said: "We can confirm that after the red flag, a number of people entered the track. All have been removed safely and a number of arrests have been made. We continue to ask people to be extra vigilant and report anything suspicious to us."
Drivers on protesters: 'F1 can do more'
Carlos Sainz sealed his first Formula 1 victory in an incident-packed race, with Sergio Perez claiming second ahead of Lewis Hamilton, with the leading trio all having differing views about the on-track protest.
"I just don't believe jumping onto an F1 track is the right way to do it," Sainz said. "Yes, I support the cause, but I don't think that's the right way to protest. You could generate an accident."
Perez added: "It's great to see people fighting for their cause. But we don't want to see people at risk. I'm sure Formula 1 can do more."
Hamilton said post-race that he "loved that people are fighting for the planet and we need more people like them", although Mercedes quickly released a follow-up statement to clarify the seven-time world champion's comments.
"Lewis was endorsing their right to protest but not the method that they chose, which compromised their safety and that of others," Mercedes confirmed.
Northamptonshire Police and Silverstone issued a warning earlier in the week to deter any potential protests ahead of race day, following intelligence received that individuals may attempt to access the track.
Event Commander, Chief Inspector Tom Thompson, said after the race: "I'm really disappointed that this group of people ignored our warnings prior to race-day and made the incredibly dangerous decision to enter the track.
"We offered to facilitate a peaceful event at the circuit, but they instead chose to put the lives of the drivers, marshals and volunteers at risk. It is incredibly disappointing that anyone would make the decision to do this.
"Thankfully we had plans in place for an eventuality such as this and the group were swiftly removed and arrested by our officers. All seven are currently in custody where their details are being ascertained.
"Finally, I would like to thank all of the officers and staff, as well as our partners, who have worked tirelessly on this policing operation. Generally we have had very low crime rates, today's incident was dealt with effectively and efficiently, and I could not have asked for more."