(CNN) Japan Airlines has moved to update its rules on drinking alcohol after its pilots failed breathalyzer tests in a series of incidents.

It has been reported that Japan Airlines pilots have failed breathalyzer tests 19 times since August 2017, when a more sensitive breathalyzer was introduced for in-house checks.

Japanese newspaper Mainichi Shimbun Thursday cited unnamed airline officials in a report that said failed tests resulted in delays to 12 domestic flights.

Passengers were told the delays were due to "crew health conditions," and staff made no mention of alcohol levels.

Japan Airlines introduced new breathalyzers in August 2017.

The latest report follows news that a Japan Airlines pilot admitted being almost 10 times over the legal alcohol limit at London Heathrow airport in October.

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