Ligita Karnilajeva, a 69-year-old passenger from Lithuania, said those on board had been told of a security alert at Kaunas, but the flight had still gone smoothly.

She said: "I only got worried when we were landing and told that we hadn't landed in Luton, but at Stansted.

"I was worried because I could see lots of police and armed forces from the window of the plane.

"Everybody started taking pictures and phoning everyone.

"We were told to leave the plane and people around me seemed more scared than me.”

Another passenger, Jonathan Zulberg, said the flight had been delayed for up to 40 minutes in Lithuania.

"When we were allowed to board we saw fire engines and a police car but weren't told anything and we took off," he said.

He said a stewardess told him there had been a bomb threat made in Lithuania but other passengers learned that only when the captain made an announcement after the plane had landed in Britain.

He said: "First (the) pilot told us of diversion. Then only once landed after about 5-10 mins pilot made announcement of bomb threat.

"When I heard I was pretty surprised the plane was allowed to take off."

A spokesman for Ryanair confirmed take-off at Kaunas had been delayed after Lithuanian authorities received a suspected hoax security alert.

"Police carried out a security search and cleared the aircraft to return to service, customers boarded and the flight departed to Luton.