The “tefillin terrorists” have struck again.

A group of Mexican Jewish tourists sparked a security alert on an Alaska Airlines flight to Los Angeles after they began putting on tefillin and reciting Jewish prayers.

Concerned airline staff placed the cockpit on lockdown for the rest of the flight, then arranged for the FBI, several fire engines and police to meet the men when they landed.

The men were questioned but released without being arrested when it was determined they were not a threat.

A spokesperson for the airline said: "Shortly after takeoff, a flight attendant saw what she believed was unusual behaviour from three passengers.

“[They] were praying aloud in Hebrew and were wearing what appeared to be leather straps on their foreheads and arms."

The incident followed a similar one on a New Zealand ferry in December. Armed police detained an Orthodox passenger after the man’s tefillin boxes were mistaken for an explosive device.

In September security officers detained a religious traveller after discovering a suspicious object in his luggage. It later turned out the object in question was a shofar.