AFP/Brussels

Belgian police arrested 16 people in a wave of anti-terrorism raids but key Paris attacks suspect Salah Abdeslam slipped the net, with Brussels set to remain under security lockdown on Monday.

Schools and the metro will be shut as Brussels stays at the highest possible alert level over what Prime Minister Charles Michel called a "serious and imminent" threat of attacks similar to those that killed 130 people in France.

Police on Sunday carried out 19 raids in Brussels and three in the industrial town of Charleroi, detaining 16 people, prosecutors said, while the driver of a car was injured after police fired two shots when the vehicle drove at officers.

"Salah Abdeslam was not caught during the raids," federal prosecutor spokesman Eric Van Der Sypt told a press conference just after midnight, meaning Europe's most wanted man remains at large.

Abdeslam's elder brother Brahim blew himself up outside a Paris bar in the November 13 attacks.

No arms or weapons were found in the raids, prosecutors added.

Armed officers and troops have been patrolling the near deserted streets of the tense Belgian capital all weekend after the government raised the terror alert to the highest level of four in the city.

The European Union and NATO, which are based in Brussels, both said they would increase security and urged non-essential staff to work from home on Monday.

Michel said the Brussels metro system would remain shut and schools and universities would be closed over concerns that jihadists were planning a repeat of the Paris gun and suicide bombing attacks on November 13.

- 'Serious and imminent' -

"What we fear are similar attacks, with several individuals in several places," Michel told reporters.

"The threat is considered serious and imminent," he said, adding that the rest of the country, including Brussels airport, would remain on security alert level three, meaning an attack is considered possible and the threat credible.

Officials will review the situation again on Monday.

The historic Grand Place square in central Brussels, usually bustling, was virtually empty at the weekend, with business badly hit in the run-up to Christmas as anxious residents heeded warnings to stay home.

With a massive manhunt on for several suspects linked to the carnage in Paris, Belgian police urged the media and social media not to show live footage of the police operations taking place Sunday evening.

Many Belgians responded in light-hearted fashion by tweeting pictures of cats under the hashtag #BrusselsLockdown.

Interior Minister Jan Jambon earlier said the authorities were looking for "several suspects" and not just for Abdeslam, who is thought to have slipped past French security forces after taking part in the Paris attacks, which were claimed by the Islamic State (IS) group.

French police meanwhile released a photo of the third of three men who blew themselves up outside France's national stadium during the rampage, which also targeted the Bataclan concert hall as well as a string of bars and restaurants.

The man in the picture passed through Greece with one of the other suicide bombers, carrying a Syrian passport in the name of Mohammad al-Mahmod, a source close to the investigation said.

- Obama 'not afraid' -

With the world on edge over the jihadist threat, US President Barack Obama said the most powerful tool in the fight against IS was to say "that we're not afraid".

He added that he would go ahead with a December visit to Paris for UN climate talks and called on other countries to show similar resolve.

French President Francois Hollande will embark on a diplomatic offensive in the coming days in a bid to forge a broad anti-IS coalition.

He will host Britain's David Cameron Monday before meeting Obama in Washington on Tuesday, holding talks with Germany's Angela Merkel in Paris Wednesday and Russia's Vladimir Putin in Moscow on Thursday.

The UN Security Council on Friday authorised "all necessary measures" to fight jihadist violence after a wave of deadly attacks, including the downing of a Russian aircraft in Egypt with the loss of 224 lives and the storming of a luxury hotel in Mali that left 19 dead.

Meanwhile, Eagles of Death Metal, the Californian band that was playing at the Bataclan where 89 people were massacred, spoke for the first time since the attacks, with singer Jesse Hughes saying that many fans died tyring to protect their friends.

"So many people put themselves in front of people," he said in an excerpt of an interview with Vice.com.

The suspected ringleader of the November 13 attacks, Abdelhamid Abaaoud, died in a massive police raid in Paris on Wednesday.

He was a notorious Belgian jihadist thought to be fighting in Syria, and his presence in Europe has raised troubling questions about a Europe-wide breakdown in intelligence and border security.

Questions remain too over the role played by Belgian-born Abdeslam -- who used to run a bar with his brother Brahim in Brussels.

A third brother, Mohamed Abdeslam, told Belgian TV on Sunday he believed Salah had at the last moment decided not go through with the attack.

He said the family wanted him to give himself up.

"That way he can give us the answers we seek, our family and the families of the victims," he said.