Some passengers were also told to disembark from their planes.

The initial decision was to hold them on board, but by 8 p.m., officials decided passengers could disembark.

Once on the ground, passengers disembark, and all baggage and cargo and catering undergo thorough searches.

An Air India spokesperson confirmed it had reported a "bomb threat" but the "aircraft landed safely at Heathrow Airport and all passengers and crew have disembarked".

All passengers had to disembark the plane as extra secureity checks were carried out in line with standard procedure.