A London-bound flight of Biman Bangladesh Airlines was forced to divert to Sofia, Bulgaria on Friday due to an onboard sick passenger.

The immediate and prompt action of the flight captain saved the passenger's life, said a Biman official.

The passenger was supposed to travel on last Wednesday. But he was offloaded due to lack of fitness certificate, sources at Biman told The Daily Star.

But the passenger managed a certificate from a local hospital in Sylhet and Biman's traffic officials accepted it and put the passenger on the flight, added the sources.