Northamptonshire Police and Silverstone circuit said the four were detained by security inside the venue perimeter. "Officers are working closely with Silverstone Circuit and conducting a full investigation," they said.
The race was closed to spectators due to the COVID-19 pandemic.
Extinction Rebellion UK posted a picture of the banner on Twitter and the words: "Today at the #BritishGP we sent a message: #ActNow this is a #ClimateEmergency and we're way off track." (Reporting by Alan Baldwin; editing by John Stonestreet)