AMSTERDAM, Netherlands (AP) _ Dutch F-16s escorted a Northwest Airlines flight bound for India back to Amsterdam's Schiphol Airport on Wednesday, and authorities detained several passengers for questioning, an airport spokeswoman said.

The pilot of the aircraft radioed Schiphol for permission to return and a military escort as it was flying over Germany shortly after leaving Amsterdam, said spokeswoman Pamela Kuypers.

Rick Hirs, a spokesman for the customs police at Schiphol, said it was not clear why the plane had returned. ``We don't know yet. We are interviewing passengers and crew members,'' he said.

Hirs said nobody on the plane had been arrested, and there were no injuries.

The Dutch National Terrorism Coordinator's Office had been informed of the incident but said there was no cause to raise the national threat level, said spokeswoman Judith Sluiter.

``It is the same as it was before _ light threat,'' said Sluiter.

It was not immediately clear how many passengers were on board the plane, but a Northwest DC-10 has a seating capacity of 273, and Kuypers said the plane was full ``as far as I know.''

Kuypers said the aircraft parked at the gate when it returned to allow all other passengers to disembark.

Last year, a British Airways flight returned to Schiphol in similar circumstances, but it turned out to be a false alarm.