BRUSSELS - Belgian authorities on Saturday charged three men with "attempted terrorist murder" after raiding dozens of homes in sweeping anti-terror raids linked to a reported threat to fans during a Euro 2016 football game.

Named by prosecutors as Samir C., Moustapha B. et Jawad B., the trio were among 12 people detained during the overnight raids, hours before thousands of people gathered around screens to watch Belgium play Ireland.

The three have also been charged with "participation in the activities of a terrorist group", while the nine others were released after questioning, prosecutors added.

The areas searched included neighbourhoods in Brussels where the jihadists behind the gun and bombing attacks in Paris on November and suicide bombings in Brussels in March had planned their assaults.

Prosecutors said they were responding to a need for "an immediate intervention".

Flemish commercial broadcaster VTM reported that the swoop was connected to a threat linked to Belgium's fixture against Ireland, held Saturday afternoon in Bordeaux, France. No incidents were immediately reported after the match which ended with a 3-0 defeat for the Irish, sending Belgians into the streets in celebration.

"Over the coming hours we are going to take additional and updated security measures," Prime Minister Charles Michel said after a national security council meeting to discuss the threat.

But public events planned in the coming days would go ahead, he said, declaring: "We want to continue living normally."

Forty people were initially detained and 152 garages searched in Friday night's raids in Brussels, Flanders and Wallonia.

VTM said the threat was chiefly to public fan zones where supporters follow Euro games on giant screens.

The raids "passed off without incident," prosecutors said in a statement, adding that no arms or explosives were found.

Belgium is still reeling from the Islamic State suicide bombings at Brussels airport and on the city's metro on March 22 which killed 32 people and wounded hundreds more.

Officers in Flanders moved on the town of Zaventem close to Brussels airport while in Brussels there were raids in the suburbs of Molenbeek, Schaarbeek and Forest, all closely associated with the perpetrators of both the Paris and Brussels attacks.

Molenbeek is notorious for being a hotbed of Islamic extremism where Salah Abdeslam, the only surviving member of the 10-man jihadist team that attacked Paris, killing 130 people, hid out for months until his dramatic arrest on March 18.

One of the searches in Wallonia was conducted in the area of Fleurus close to Charleroi airport -- Belgium's second international air hub -- and a region that also hosts part of the country's nuclear industry.

Euro 2016 host France is on maximum alert after an assailant previously convicted for jihadism killed a police officer and his partner on Monday. In Belgium, the latest raids have raised tensions in a country already dogged by the threat of terrorism.

Belgian media reported Wednesday that police had warned that IS fighters had recently left Syria to carry out attacks.

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"They would separate into two groups, one for Belgium, the other for France, to attack in pairs," an official document revealed by the La Derniere Heure newspaper stated, describing the threat as "imminent".

On Saturday, a source close to the Belgian authorities confirmed to AFP that several leading political figures have recently had their security increased.

According to state broadcaster RTBF and daily Flemish newspaper Het Nieuwsblad, 30 people and their families have had their personal security stepped up since Friday, including the prime minister, interior minister and justice minister.

Despite the disclosures, Belgium's terror level remains at level three meaning that an attack is considered "possible and probable". The highest, level four, would mean that the threat is "serious and imminent".

Belgian media also reported Saturday that a 30-year-old man arrested and charged Friday in connection with the Brussels attacks had worked at Brussels airport.

The suspect, named as Youssef E.A., worked for an airline catering company and had access to planes on the tarmac, the Flemish daily Het Nieuwsblad and several French-language titles reported.

The federal prosecutor's office declined to confirm the report.

The man, who has been linked to metro bomber Khalid El Bakraoui and another suspect, was charged Friday with "participation in the activities of a terrorist group, terrorist murders and attempts to commit terrorist murders, as a perpetrator, co-perpetrator of accomplice".