Police arrested 12 of the 149 passengers on flight 42 to Mumbai, which turned back to Amsterdam due to security concerns after the crew reported suspicious behaviour.
Two Dutch fighter jets accompanied the plane back to Schiphol after rendezvousing with the passenger plane as it entered Dutch airspace.
"They will be interrogated in the coming hours by police investigators," a police spokesman said.
Asked whether a suspected terrorist plot could be ruled out, he said: "We don't want to get ahead of ourselves".
Suspects held
Dutch police can hold suspects for three days without charge, extended by another three days in special circumstances. The authorities expect to provide more information tomorrow.
Eyewitnesses said that those arrested were not following airline security rules and were exchanging mobile phones which had made other passengers uneasy.
"They were not paying attention to what the flight attendants were saying," an unnamed female passenger said on NOS television.
Security has been increased at airports worldwide in the last two weeks after British police said they had foiled a plot by British Muslims to blow up planes in the mid-Atlantic using liquid explosives disguised as drinks.
But the return of the Northwest plane did not lead to heightened security but had not affected other flights at Schiphol, Europe's third largest cargo airport and fourth biggest passenger hub.
Dutch airport officials said the Northwest pilot decided to turn back his 273-seat DC10-30 when it was in German airspace.
A Northwest spokeswoman said the other passengers were allowed to go free and are staying in local hotels, adding Northwest would try the flight to Mumbai again tomorrow.
Security level
The Dutch Defence Ministry said it was keeping the national counter-terrorism coordinator informed.
The government has not decided to take any extra security measures, it said.
The Netherlands' security alert level has been at "substantial" since bombings in London last year, the second highest in a four-stage warning system.
The Dutch secret service AIVD warned in March that the war in Iraq and the presence of Dutch troops in Afghanistan might motivate possible attacks and encourage the recruitment of home-grown Islamist militants.
British prosecutors investigating the plane bomb plot foiled earlier this month announced on Monday they were charging 11 people after police found bomb-making equipment, suicide notes and "martyrdom videos".
Ten other people were still being held, while another person has been released without charge.