Belgian troops guard a community center in the Jewish neighborhood in Antwerp, after the Charlie Hebdo attacks in January 2015 | Laurens Cerulus Belgian raid renews worries about terrorism The seat of the EU is a ‘weak link’ on security.

Belgian police on Saturday afternoon carried out raids in a northern neighborhood of Brussels, arresting an unspecified number of suspects.

The operation in Molenbeek, which has a large Muslim population, was connected to Friday night's attacks in Paris, the Belgian federal prosecutor said in a statement.

The terrorist attacks in France cast an uncomfortable spotlight on neighboring Belgium, considered by intelligence officials a "weak link" in Europe's counterterrorism efforts. The country has struggled to track hundreds of locals who have gone to fight with radical groups in Syria.

The prosecutor said Belgian police acted on Saturday after police in Paris found a rental car with Belgian plates that was likely used by the attackers parked near the Bataclan concert hall, where 89 people were killed.

Belgian authorities refused to comment on a report in Le Soir newspaper that three of the terrorists were from Molenbeek, which has a large Muslim population.

Belgian Prime Minister Charles Michel told Belgian broadcaster VTM Saturday evening that "We're on alert with our security services, and with the investigation. We have an important meeting this evening and have decided on additional security measures."

Earlier in the day, the country had put its police on high alert Saturday, imposing stricter controls on its border with France and boosting police presence at key locations.

Speaking to public radio Saturday morning, Interior Minister Jan Jambon said the country "shouldn't panic." A crisis center is monitoring the situation, but "based on the information we have, there are no direct indications to increase our security level," he said.

Last week at a POLITICO conference on dealing with extremism, Jambon said that Belgium had gotten a better grip on the problem in most Belgian cities in the past year, but said the exception was Brussels. He blamed a fragmented police force.

“Brussels is a relatively small city, 1.2 million,” Jambon said. “And yet we have six police departments. Nineteen different municipalities. New York is a city of 11 million. How many police departments do they have? One.”

Brussels has popped up on intelligence services' radar several times in the past year. The guns that Islamic State terrorists used in the attack on the French satirical magazine Charlie Hebdo in January were most likely bought in Brussels, court evidence showed.

Last January, soon after that strike in Paris, Belgian police uncovered a terrorist cell in the depressed industrial city of Verviers. In May of 2014, a gunman killed four people at the Jewish Museum of Belgium in Brussels. Belgian authorities are trying Mehdi Nemmouche, a French citizen who travelled to Syria, for the murders.

Government buildings and Jewish schools have been more closely guarded by Belgian troops since then.

Belgium has one of Europe's most fraught records with Islamic radicalism. Belgium accounts for as many as 400 of the fighters who have joined Islamic State in Syria, the highest per capita rate of any European country, according to one analysis. About 6 percent of the country's 11 million people are Muslims.

Earlier this year, a group called Sharia4Belgium, which aims to impose Islamic law in Belgium and has been accused of recruiting fighters for ISIL, was designated a terrorist organization and its spokesman sentenced to 12 years in prison.

In the wake of the French attack, the country's prime minister, Charles Michel, advised Belgians to avoid trips to Paris. "This tragedy is an attack on our fundamental values," Michel said.

Belgian Foreign Minister Didier Reynders said French authorities had confirmed two Belgians were among the 127 people killed in the attack.