Passengers on an international flight feared the worst after their pilot collapsed in the cockpit 30,000 feet in the air.

Thomson Holiday flight 1714 was 16 minutes into its journey from Newcastle, UK to Larnaca, Cyprus when a passenger saw the pilot "lying prostrate on the floor", according to The Sun.

Panic and fear spread through the plane when crew members were seen rushing to collect oxygen cylinders to take into the cockpit.

"It was terrifying," one passenger, a father of one, told The Sun.

"I glimpsed inside the cockpit door. There was coffee all over the floor and it looked like the guy had collapsed.

"He was lying prostrate on the floor. It's not what you want to see happening at the front of the plane."

The plane was diverted to Sofia, Bulgaria and passengers will spend the night in a hotel ahead of another scheduled service from Bulgaria to Cyprus.

Another passenger who spent $3,560 for a family week-long break said: "Money wasn't what I was thinking about when the pilot collapsed.

"He was wheeled out of the cockpit and off the plane after our emergency landing before being placed on a stretcher and taken off to hospital."

Thomson Airways told The Sun: "We can confirm that as a result of one of our pilots feeling unwell, the decision was taken to divert the Newcastle to Larnaca, Cyprus flight last night.

"A priority landing was requested at Sofia, Bulgaria which was the closest airport and the pilot was taken to a nearby hospital to be assessed.

"We would like to thank all of our customers for their patience and we are working to get them on their holiday as quickly as possible.

"The welfare of all customers and crew travelling with us is our priority at all times."