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The Serious Fraud Office (SFO) has launched a criminal investigation into suspected fraud at a UK-based aircraft parts supplier.

Investigators from the SFO carried out a raid early on Wednesday, making one arrest.

Earlier this year, UK, US and European regulators issued alerts to firms to check parts from AOG Technics.

They were asked to trace the provenance of parts directly and indirectly supplied by the firm.

AOG has supplied parts for the world's best-selling passenger aircraft engine since 2015 to a number of major airlines globally.

Ryanair, as well as US carriers such as American Airlines, United Airlines and Delta, are some of the operators investigating engine parts that may have come from AOG Technics, according to reports by Bloomberg.

None of the above airlines immediately responded to a ����ý request for comment.

Jet2, EasyJet, British Airways and Virgin Atlantic told the ����ý that AOG was not one of their suppliers.

British Airways and Virgin Atlantic do not operate aircraft powered by the CFM56 engines in question.

While it had previously been reported that Tui had been affected, the airline said on Wednesday that it is not an AOG customer.

It confirmed that it had previously been sent one single plane as a "lease-in", where one engine was affected - but regular maintenance checks put the part in doubt, which was then replaced.

The UK aviation watchdog, the Civil Aviation Authority (CAA), , which prompted some companies to take a small number of planes out of service temporarily as a precaution.

It is understood that any affected airlines in the UK have since had the parts replaced and have resumed flying.

AOG Technics mostly sold to overseas companies that install airline parts but some UK airlines were also affected, the SFO said.

The fraud watchdog's director Nick Ephgrave said the investigation dealt with "very serious allegations of fraud", with "potentially far-reaching consequences".

The body is working with the CAA and other regulators in a bid to "establish the facts as quickly as possible", it said.

A spokesperson for the CAA said that it had been working closely with watchdogs in the US and Europe to prevent any safety issues from coming up.

Independent aviation expert John Strickland said that he could not recall "a similar situation in my career".

"It is a cause for concern for manufacturers and airlines alike," he added.

But Mary Schiavo, former inspector general of the US Department of Transport, previously told the ����ý's World Business Report that passengers should feel reassured if they were flying with a major, reputable airline from a country with a big aviation industry, like the US or UK.

She described airlines as the "first line of defence" and pointed out that laws require them to isolate, put a red tag on and lock up in a secure vault any potentially "bogus parts".

The ����ý could not immediately reach AOG Technics for a comment.