A British Airways flight has reportedly been evacuated after smoke filled the cabin minutes before it was due to land.

Passengers shared video and photos of the experience after a British Airways flight from London's Heathrow landed at Valencia in Spain.

A spokesman for the airline said: "We can confirm that British Airways flight BA422 from Heathrow to Valencia has been involved in an incident today. The aircraft, an A321, has landed and all customers and crew have disembarked. British Airways teams are assisting customers who are in the airport terminal.”

The Europa Press news agency said three people were treated for smoke inhalation and 16 passengers were treated for anxiety and chafing suffered when they slid down inflatable emergency slides.

Gayle Fitzpatrick, from Glasgow, Scotland, who was on holiday with her husband Stephen, described the moment smoke entered the plane's cabin.

”It was very scary. The flight was just ending, and with 10 minutes to go the flight started descending rapidly as smoke started to fill the cabin,” she said.

"A detector was going off saying the cabin was filling with smoke. It was like a horrible white acrid smoke.

"There was chat it was an air-conditioning unit. There were no communications from the crew, some of which started to wear full oxygen masks and protective fire wear.

"Eventually they managed to open the emergency doors and told us to go down the chutes.

"There were fire engines waiting and then we were all ushered into a bus then to the airport.

"We are still waiting to hear what happened. People were crying and hyperventilating. It was genuinely scary."

She added: "We were not told it was an emergency until we had landed and they were trying to open the cabin doors for passengers to jump down the chutes."