Police investigating the suspected chemical incident which led to the evacuation of London City Airport have discovered what is “believed to be a CS gas spray”, a spokesman said.
The find came after police and firefighters scoured the airport following the alert, which saw dozens of passengers treated for breathing difficulties.
The airport spokesman said it was unclear what had caused the chemical incident, but officers were “investigating whether it was the result of an accidental discharge of the spray”.
Hundreds of passengers were ordered to leave the terminal building and no flights were able to take off or land.
Several incoming flights from destinations including Frankfurt, Amsterdam, Belfast City and Paris were diverted to other airports.
A London City Airport spokeswoman said the cause of the alarm was being investigated. She could not confirm whether a fire had been discovered.
London Fire Brigade said it was called to the airport at 4.11pm on Friday.
Three fire engines and 15 firefighters were sent to the scene to work alongside crews based at the airport.