The US Federal Aviation Administration and Boeing have privately issued notifications that the fuel switch locks on Boeing planes are safe, a document seen by Reuters showed and four sources with knowledge of the matter said.

The FAA's Continued Airworthiness Notification on July 11 came after a preliminary report into Air India's Boeing 787-8 crash, which killed 260 people last month, raised questions over engine fuel cutoff switches, Reuters reported.

The FAA's notification to Civil Aviation Authorities, seen by Reuters, said: "although the fuel control switch design, including the locking feature, is similar on various Boeing airplane models, the FAA does not consider this issue to be an unsafe condition that would warrant an Airworthiness Directive on any Boeing airplane models, including the Model 787."

When asked for comment, the FAA said it did not have anything to add beyond the notification.

Boeing also referred to the FAA notification in a Multi-Operator-Message sent to the airlines in the past few days, which said the planemaker is not recommending any action, two of the sources with direct knowledge said, according to Reuters.