Roads around Heathrow Airport were blocked by an anti-racism protest on Friday, causing major delays and tailbacks.
Campaigners from group Black Lives Matter lay down across the M4 slip road to the airport beneath a banner reading: "This is a crisis."
Protests also took place near Birmingham Airport and in Manchester and Nottingham.
At midday, the Metropolitan Police confirmed four people have been arrested and taken to west London police stations where they remain in custody. A further six people have been arrested at the scene.
It said police are in the process of safely releasing these protesters who have ‘locked on’ to each other. One lane remains closed to ensure the safety of protesters and officers.
West Midlands Police said four women and one man were arrested on suspicion of obstructing the highway and public order offences on the A45 in Solihull.
The group said the protests were timed to commemorate the fifth anniversary of the death of Mark Duggan, who was shot by police during an attempted arrest in Tottenham, north London, in August 2011. The incident sparked riots across Britain.
Heathrow advised motorists travelling via the M4 to exit earlier at A312 (The Pkwy) due to delays at M4 Spur.
