The U.S. Federal Aviation Administration and Boeing have privately issued notifications that the fuel switch locks on Boeing planes are safe.

India on Monday ordered its airlines to examine fuel switches on several Boeing models, while South Korea said it would order a similar measure, as scrutiny intensified of fuel switch locks at the centre of an investigation into a deadly Air India crash.

The US Federal Aviation Administration (FAA) has said the fuel control switches in Boeing aeroplanes are safe, following their reported involvement in a fatal Air India crash that killed 260 people in June.