Dutch Crown Prince Willem-Alexander became Europe's youngest monarch on Tuesday after his mother, Queen Beatrix, abdicated and his country hailed the avowedly 21st-century king with a massive, orange-hued party.

"I Queen Beatrix... abdicate in favor of my son Willem-Alexander," the act said, as read out before the signing that was broadcast live from the Amsterdam palace.

The Dutch government has raised its terror threat level from "limited" to "substantial," saying Dutch citizens are traveling to Syria to fight in the civil war and could return battle-hardened, traumatized and further radicalized.

The country's National Coordinator for Security and Counterterrorism said in a statement Wednesday "the chance of an attack in the Netherlands or against Dutch interests abroad has risen."

At least 60 people were injured, up to 20 of them seriously, in a two-train collision Saturday outside Amsterdam, Dutch transport police said.

"There are 60 people injured -- some 15 to 20 badly," police spokesman Ed Kraszewski told Agence France Presse, after the head-on smash near Sloterdijk in the western suburbs of Amsterdam.

Around 480 people were stranded on a high-speed train linking Amsterdam to Paris after a fire in its engine that hospitalized the train's driver, the rail company and emergency services said.

Some 20 high-speed TGV, Thalys and Eurostar cross-Channel trains have been diverted as a result of the incident, each suffering a delay of "around 30 minutes,” national rail operator SNCF said.

Airport police evacuated two terminals at Amsterdam's busy Schiphol Airport on Monday after receiving a bomb threat, a spokesman for the force said.

Officers evacuated two departure halls as they investigated the threat, said airport police spokesman Martijn Beelen. He gave no further details of the threat.

An elephant in Amsterdam's zoo has made history after being fitted with a jumbo-sized contact lens following an eye injury, a statement said Monday.

"Win Thida is the first elephant in Europe with a contact lens," the Artis zoo said on its website.

A placard reading "Bed Peace", which was made by former Beatle John Lennon during his peace-in with wife Yoko Ono at a Canadian hotel, has fetched almost £100,000 at a London auction.

The sign, sold at Christie's auction house on Tuesday, was bought by an anonymous telephone bidder for £97,250 ($153,835, 113,670 euros).

Dutch brewer Heineken published a one percent climb in net profit for the third quarter Wednesday, saying strong sales in Africa and elsewhere offset the impact of poor summer weather in Europe.

Net profit reached 525 million Euros (U$731 million) in the July-September period, while sales grew slightly by 0.6 percent from last year to 4.65 billion Euros, despite the disadvantage of a strong euro, the company said.

The Van Gogh Museum says it is shutting its doors for six months for renovations starting next year, the latest major Dutch museum to close for reconstruction.

Director Axel Rueger said Friday the museum's most important paintings will move to the Hermitage Amsterdam so they can still be viewed during the work, scheduled to last from October 2012 through March 2013.

Dutch airline KLM announced on Wednesday that it will use a biofuel generated from used cooking oil to power more than 200 commercial flights between Paris and Amsterdam starting in September.

"There will be 50 percent traditional kerosene and 50 percent biofuel extracted from used cooking oil," KLM spokesman Gedi Schrijver told Agence France Presse, adding that KLM is the first airline to use this type of fuel in commercial flights.