Two Dutch fighter planes accompanied a US Northwest Airlines plane bound for Mumbai (Bombay) back to Amsterdam's Schiphol airport, officials said.

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

Security has been increased at airports worldwide after British police said on Aug 10 they had foiled a plot to blow up planes in the mid-Atlantic using liquid explosives disguised as drinks.

Dutch news agency ANP quoted police as saying a number of people had been taken off the Northwest plane and were being questioned. Airport information said none of the passengers on the plane were being allowed to leave yet.

Northwest Airlines said the plane was bound for Mumbai and declined to comment further. An air traffic control spokeswoman said the flight was NW0042, a 273-seat DC10-30 plane.

Last month serial bomb blasts hit commuter trains in Mumbai, killing more than 180 people. Indian police said on Tuesday they had foiled another possible attack in the city after they shot dead a suspected Pakistani national.

Dutch police were not immediately available to comment. A spokewoman for Dutch counter-terrorism said the security alert had not been changed at Schiphol airport at midday on Wednesday.

Schiphol airport is Europe's third largest cargo airport and fourth biggest passenger hub.

An Iberian Airlines flight bound for Madrid was turned back to the Netherlands in April after a woman raised the alarm about a passenger she thought was acting suspiciously. The passenger was later cleared of any wrongdoing.Reuters