An easyJet flight to London with more than 100 people on board made an emergency landing after the co-pilot, a member of cabin crew and some passengers were overcome by what the airline described as a “smell event”.

Flight EZY2278 from Palma, Majorca, to Luton on October 3 was forced to divert to Paris where paramedics met the aircraft and the first officer was taken away in an ambulance.

Asked by the Sunday Times if this was an “aerotoxic incident” caused by fumes, easyJet said: “No, this was a smell event and we do not categorise any event as aerotoxic. This is not a classification easyJet uses.”

One passenger, a fashion designer called Isabelle, said less than an hour before the flight was due in Luton the captain “said we had to land because too many people were ill. He said his co-pilot was really unwell, so we needed to land and check what was going on.”

She said that as soon as the aircraft landed at Charles de Gaulle airport at nearly 2am “six doctors or paramedics came in. They helped the pilot, then the passengers. They came in with oxygen and helped them in the plane. A little boy in the back was vomiting.”

An official with a measuring device entered the cabin to check the air quality; after a short while the remaining passengers were ordered out, she added.

The flight, which had left Palma at 11.45pm, is recorded as “cancelled” by flight tracking websites. The aircraft used – an Airbus A319 – later flew without passengers to London.

The airline said: “We can confirm the captain took the decision to divert to Paris due to some passengers and crew feeling unwell. He took the decision as a precaution only and the aircraft landed routinely.”

Engineers found a “leakage of hydraulic fluid” in the tail section, “of which a very small amount could trigger a smell”, easyJet added.

The leaking component was replaced and the aircraft given a “technical clean”, with all the cabin air recirculation filters and seat headrest covers replaced.

Campaigners claim “aerotoxic syndrome” from contaminated cabin air accounts for the premature retirement, ill-health and even deaths of pilots and crew. Frequent flyers and young children can also be at risk, it is claimed.

Aircrew unions are involved in about 100 civil court actions for death and injury allegedly caused by cabin air. All airlines deny that fume events have long-term effects.