Paris Urges Nationals to Exercise 'Utmost Caution' after IS Threat, EU Boosts Security

France on Monday urged nationals living in or traveling to some 30 countries to exercise "utmost caution" after the Islamic State group called for Muslims to kill civilians whose governments were acting against the jihadists.

The foreign ministry said it had sent a warning note to its embassies "in around 30 countries" in Africa and the Middle East.

Earlier on Monday, Paris sought to reassure its citizens that it was prepared to head off attacks on home soil in the wake of IS' threat.

"France is not afraid," Interior Minister Bernard Cazeneuve said repeatedly during a televised statement in response to the remarks.

"France is prepared to respond to their threat," said Cazeneuve, adding security forces were "fully mobilized."

"This is not the first time France has been threatened by terrorist groups who attack the values of tolerance ... respect for human rights and democracy, which France has upheld through its secular history," he said.

France on Friday joined the U.S. in carrying out air strikes against the IS group which controls large areas of Iraq and Syria where it has declared a "caliphate."

"If you can kill a disbelieving American or European -- especially the spiteful and filthy French -- or an Australian, or a Canadian or any other disbeliever... including the citizens of the countries that entered into a coalition against the Islamic State, then rely upon Allah, and kill him," said Abu Mohammed al-Adnani, the group's spokesman.

In a message released online in several languages, the IS spokesman gave tips on how to kill citizens of enemy nations without military equipment.

"Smash his head with a rock, or slaughter him with a knife, or run him over with your car, or throw him down from a high place, or choke him, or poison him." 

"If you are unable to do so, then burn his home, car, or business. Or destroy his crops. If you are unable to do so, then spit in his face."

France is increasingly concerned about the number of citizens traveling to fight in Iraq and Syria who could return and pose a threat on home soil.

The lower house national assembly on Friday approved an "anti-terrorism" bill which will usher in a travel ban on anyone suspected of planning to wage jihad.

Cazeneuve said the bill would also allow for security services to be "better armed."

"Even if there is no such thing as zero risk, today we are taking 100 percent precautions."

Meanwhile, the European Union boosted security at its Brussels headquarters on Monday even as authorities downplayed reports that jihadists arrested after returning from Syria were planning to target the building.

Belgian judicial officials said materials which could be used to make explosive devices were found in a raid in the Netherlands but stressed there was no proof of a plot to attack the European Commission building.

However extra security personnel were posted at the entrance to the Commission building in the EU district of central Brussels on Monday, checking the security passes of everyone entering, Agence France-Presse reporters saw.

Belgian authorities confirmed they had made two arrests under anti-terrorism laws as they sought to prevent jihadist fighters or sympathizers with the Islamic State extremist group from carrying out attacks.

Dutch public broadcaster NOS said Saturday said that the two -- a man and a woman of Turkish descent from The Hague -- had been picked up when they arrived in Brussels. The two allegedly had spent time in Syria.

Meanwhile an internal email from Commission vice president Maros Sefcovic, who oversees security at the EU's executive branch said he had decided to increase security in light of the reports.

"Given the current international situation, and as a precaution, I have decided to raise the security level in the Commission buildings. If necessary further security measures will be put in place," the Belga news agency cited the email as saying.

The Commission is the public face of the European Union and it has one of the most high-profile buildings in Brussels, housing several thousand officials and the top brass in charge of the daily running of the 28-nation bloc.

Spokesman Jonathan Todd said the Commission "constantly monitors" the security situation but that Belgian authorities had confirmed there was no specific threat against the building. 

"We do not comment on internal security measures taken by the Commission, we never have done in the past and we're not going to start doing so now for very very obvious reasons," he told a daily briefing. 

The Brussels federal prosecutor's office said reports that explosives had been found in raids in Belgium were "incorrect".

"However, in one of the searches in the Netherlands, materials were found which could potentially have been used to make an explosive device -- although they were not explosives and it could not be determined if this concerned an explosive device ready to be used," it said in a statement.

Some of the people under investigation were found to be living near EU institutions but there was "no solid evidence that this could be linked to a concrete plan for a bomb attack," it added. 

The two suspects remained in detention, the prosecutor's office added.

Belgium, like several European countries, is increasingly worried about its nationals going to fight in Syria and Iraq for fear they will return home battle-hardened and even more radicalized, posing a threat to security.

It is estimated some 400 Belgians may have done so, while about 90 have returned home.