A man has been arrested after what emergency services described as a "potential hazardous materials incident" at Heathrow Airport.

The west London airport's Terminal 4 check-in area was evacuated on Monday, after around 20 people reported injuries.

Specialist officers attended the scene alongside the London Fire Brigade and London Ambulance Service and conducted a thorough search of the area.

Following the search, Metropolitan Police officers located a cannister of what is believed to be CS spray.

"It is thought that this substance caused a reaction to those within the airport," the Metropolitan Police said in a statement.

The force said a 57-year-old man had been arrested on suspicion of possession of a firearm (CS spray) and causing a public nuisance.

He remains in police custody.

See Full Page