Eleven people have been injured after a passenger jet en route to London Heathrow was forced to make an emergency landing in Porto following a mid-air smoke alert.

The TAP Air Portugal flight, carrying 194 passengers from Lisbon, was diverted after smoke was detected onboard around 4.45pm on Tuesday (March 11). The aircraft made a safe emergency landing at Francisco de Sá Carneiro Airport in Porto just after 5pm.

According to reports in Portuguese media, nine passengers were taken to hospital suffering from smoke inhalation, while two others received medical assistance near the aircraft. Portuguese Civil Protection officials said the passengers and crew required urgent medical support following the incident.

“There are 194 passengers on board and crew and passengers are in need of urgent medical assistance,” officials told Correio da Manhã newspaper.

Around 57 emergency responders and 15 vehicles from the fire service, Red Cross, and local police rushed to the airport to support the operation.

Flight data from Flightradar24 showed the aircraft abruptly changing course about an hour into the journey, looping over western Spain before heading north towards Porto.

A spokesperson for TAP Air Portugal confirmed the plane had experienced a “technical issue” but reassured that it had landed safely. Passengers were later transferred to another aircraft.

The flight eventually departed Porto at around 9pm and safely landed at London Heathrow later that evening.

Investigations into the cause of the smoke alert are ongoing.