"Our investigation is still in a preliminary phase, it is too early to draw conclusions," a spokeswoman for the Dutch Safety Board said on Monday.
Witnesses said they saw the fire in one of the engines of the plane, which landed safely at Liege airport in Belgium, some 30 kilometres (19 miles) south of Maastricht.
The cargo plane, which was supposed to fly from the Netherlands to New York, used a Pratt & Whitney PW4000 engine, a smaller version of one on a United Airlines Boeing 777 involved in an incident on Saturday.
Boeing said on Sunday that it was recommending airlines halt flights of some older, PW4000-powered versions of its 777 airliner pending engine inspections after the United 777 suffered an engine fire and scattered debris over Denver in the United States at the weekend.
Europe's EASA aviation regulator said on Monday that it was aware of the Pratt & Whitney jet engine incidents, and was requesting information on the cause to determine what action may be needed. (Reporting by Bart Meijer and Anthony Deutsch; editing by Susan Fenton, Jason Neely and Emelia Sithole-Matarise)