LONDON — The Royal Air Force escorted a Ryanair plane to Stansted Airport, north of London, on Wednesday after the flight from Lithuania was diverted because of a security threat that the airline later said was most likely a hoax.

The flight, which originated in Kaunas, Lithuania, landed safely around 8:55 a.m., the police said, and passengers were escorted off the aircraft. Ryanair said a “suspected hoax security alert” had been flagged by the Lithuanian authorities.

Britain has been on edge after a series of terrorist attacks this year, and flights were briefly halted from Stansted on Wednesday, the airport said, but were now “arriving and departing as normal.”

It was not immediately clear why the jet had required a military escort. Loud noises were reported in the Suffolk area of England, but the police said the sounds had come from a military plane.