By Abhijith Ganapavaram and Lisa Barrington

NEW DELHI (Reuters) -India on Monday ordered its airlines to examine fuel switches on several Boeing ( BA ) 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 precautionary moves by India, South Korea and some airlines in other countries came despite the planemaker and the U.S. Federal Aviation Administration telling airlines and regulators in recent days that the fuel switch locks on Boeing ( BA ) jets are safe.

The locks have come under scrutiny following last month's crash of an Air India jet, which killed 260 people.

A preliminary report found that the switches had almost simultaneously flipped from run position to cutoff shortly after takeoff. One pilot was heard on the cockpit voice recorder asking the other why he cut off the fuel. "The other pilot responded that he did not do so," the report said.

The report noted a 2018 advisory from the U.S. Federal Aviation Administration (FAA), which recommended, but did not mandate, operators of several Boeing ( BA ) models including the 787 to inspect the locking feature of fuel cutoff switches to ensure they could not be moved accidentally.

India's Directorate General of Civil Aviation said it had issued an order to investigate locks on several Boeing ( BA ) models including 787s and 737s, after several Indian and international airlines began making their own inspections of fuel switches.

The regulator oversees the world's third-largest and fastest-growing aviation market. Boeing ( BA ) planes are used by three of the country's four largest airlines.

PRECAUTIONARY CHECKS

Some airlines around the world told Reuters they had been checking relevant switches since 2018 in accordance with the FAA advisory, including Australia's Qantas Airways and Japan's ANA.

Others said they had been making additional or new checks since the release of the preliminary report into the Air India crash.

Singapore Airlines said on Tuesday it had carried out and completed precautionary checks on the fuel switches of its 787 fleet, including planes used by its low-cost subsidiary Scoot.

A spokesperson for the South Korean transport ministry said checks there would be in line with the 2018 advisory from the FAA, but did not give a timeline for them.

Flag carrier Korean Air Lines said on Tuesday it had proactively begun inspecting fuel control switches and would implement any additional requirements the transport ministry may have.

Boeing ( BA ) referred Reuters' questions to the FAA, which did not respond to a request for comment. Boeing ( BA ) shares closed 1.6% higher on Monday after there were no recommended actions in the report aimed at operators of 787 jets or the GE engines.

Japan Airlines ( JPNRF ) said it was conducting inspections, but had also been doing so since the 2018 advisory came out.

"Any issues detected were repaired on the ground, and therefore did not occur during flight," JAL said in a statement on Tuesday.

Over the weekend, Air India Group started checking the locking mechanism on the fuel switches of its 787 and 737 fleets and has discovered no problems yet, a source familiar with the matter told Reuters on Monday.

About half the group's 787s have been inspected and nearly all its 737s, the source added, speaking on condition of anonymity. Inspections were set to be completed in the next day or two.

The Air India crash preliminary report said the airline had not carried out the FAA's suggested inspections as the FAA's 2018 advisory was not a mandate.

But it also said maintenance records showed that the throttle control module, which includes the fuel switches, was replaced in 2019 and 2023 on the plane involved in the crash.

In an internal memo on Monday, Air India CEO Campbell Wilson said the preliminary report found no mechanical or maintenance faults and that all required maintenance had been carried out.