Dutch authorities on Wednesday raised the threat of a terror attack to "substantial", saying the increased risk stemmed mainly from radicalised jihadists returning from fighting in the Middle East, specifically Syria.
"The number of those jihadists travelling from the Netherlands to Syria has rapidly increased," the National Counterterrorist and Safety Coordinator (NCTV) said in a statement.
"There is a risk that those who travel for jihad pick up experience in conflict areas and upon return to the Netherlands form a threat because they could come back radicalised, traumatised and willing to commit violence," the government's anti-terror body said.
The threat of an attack against the Netherlands or its overseas interests has grown, prompting the NCTV "to increase the threat level from limited to substantial," it added.
The Netherlands has four threat levels: minimal, limited, substantial and critical. The country last saw a substantial threat level being downgraded to limited in November 2009.
In its report released on Wednesday, the NCTV also said that the country continued to be viewed as a legitimate target by jihadists because of perceived discrimination against Muslims.
The report specifically mentioned anti-Islam far-right politician Geert Wilders, who received "negative attention in the Arab-speaking media because of his plans to put Islam back on the political agenda."
A Dutch court in 2011 acquitted Wilders on hate-speech and discrimination charges for making statements attacking Islam, including making a controversial anti-Islam movie and comparing the Koran with Hitler's "Mein Kampf."
Local media reports this month said Wilders ranked fourth on an apparent extremist death-list, recently published on the Internet.
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The flamboyant and outspoken politician lives under constant protection and his movements and private life are closely-guarded affairs.
Earlier this week, Dutch public broadcaster NOS reported that around 100 Dutch citizens were fighting in Afghanistan, Somalia and, mostly, in Syria.
"Therefore the Netherlands is one of the largest suppliers of European fighters, who have in most cases joined the Al-Nusra movement in Syria," the NOS reported.
The Al-Nusra Front, completely unknown before the rebellion in Syria that began two years ago, has been a rebel standard-bearer since mid-2012 when it became the spearhead of the insurgency ahead of the Free Syrian Army.
Al-Nusra makes no secret of its aim for Syria to become an Islamist state. Damascus accuses both Saudi Arabia and Qatar of financing Islamist groups battling the regime of Syrian President Bashar al-Assad.
NCTV chief Dick Schoof said several former fighters have returned to the Netherlands after stints in Syria.
"Those who have come back are being closely watched," he told the NOS.
Dutch police in November arrested three would-be jihadists on their way to Syria on charges of "preparing terrorist activities".
Police seized knives, a sword, a crossbow as well as backpacks, farewell letters and a large quantity of jihadist literature in the bust.