Dutch F-16s escorted a Northwest Airlines flight bound for Mumbai back to Amsterdam's Schiphol Airport on Wednesday, and authorities later detained several passengers for questioning, CNN quoting airport sources reported.

"A number of suspects were taken off the plane -- I don't know how many. They're undergoing questioning now," airport spokesperson Snoerwang said.

Agency reports said the plane was in German airspace when it was turned back.  A spokeswoman for Schiphol said the pilot had taken the decision to turn back but could give no further details.

Schiphol airport's website listed the NW0042 flight to Mumbai as cancelled, the reports said.

The plane had 149 passengers on board. Unconfirmed reports say that seven pasengers have been detained for questioning.

A Northwest Airlines spokesperson said that the flight had been cancelled and that it would be rescheduled for Thursday.