Pre-emptive raids were carried out in eastern town of Verviers against a group suspected of preparing major attack, federal prosecutor says

Counter-terrorist units foiled what was described as a jihadist plot to stage a major attack in eastern Belgium on Thursday evening, killing two gunmen and wounding another in a shootout in the town of Verviers near the German border.

The federal prosecutor, Eric Van Der Sypt, denied there was any link with last week’s attacks in Paris, but drew parallels with the Charlie Hebdo incident.

He said a terrorist outrage may only have been hours away: “This operation stopped a major terrorist attack from taking place. You could say a second potential Paris has been averted.”

All three gunmen, he said, were Belgian nationals. Police sources told Belgian television stations they had resolved to launch the pre-emptive operation against the terrorist suspects a fortnight ago after bugging the homes and cars of the men who were said to have recently returned from fighting in the war in Syria. The investigation concluded that a large-scale attack was imminent, targeting police stations.

Parallel to the scenes in Verviers, special police units carried out at least a dozen raids elsewhere in Belgium in what appeared to be well-planned operations. They focused on neighbourhoods that are predominantly populated by immigrants in at least four districts in and around Brussels, with explosives reportedly found in the western Brussels area of Anderlecht. There was no police confirmation.

The Belgian prosecutor’s office said the terrorist suspects opened fire on police in Verviers when the raid was launched. No civilians or police were hurt in the operation. The wounded suspect, arrested and taken to Brussels, was said to be a Chechen known to the Belgian authorities.

Julien Faniel (@Julien_Faniel) #verviers les gens doivent fermer leurs volets toujours pic.twitter.com/2cmNtLzN5T

The suspects fired at the special units of the federal police for several minutes, using military weaponry and handguns, before they were “neutralised”, Van Der Sypt said. “The group was on the point of committing a major, imminent attack in Belgium,” he said.

He described the three heavily armed gunmen as an operational cell that had recently returned from fighting in the war in Syria. They were preparing “imminent terrorist attacks on a grand scale”.

A total of 10 search warrants were issued for synchronised raids in Brussels, as well as Verviers at the end of a surveillance campaign that had lasted several weeks.

The outcomes of the other police search operations were not made public. Belgian journalists accompanying some of the raids said explosives had been found. Van Der Sypt said Belgium’s terror alert for the security forces had been raised to its second-highest level.

Witnesses in Verviers said they heard a series of explosions at 5.45pm and then sustained gunfire near the railway station. They looked out of their windows to see the streets full of police vehicles 500 metres from the town mayor’s offices and beside the local justice ministry buildings which include a prison facility.

The Belgian police are looking to possible links between a suspected arms dealer arrested in the southern town of Charleroi on Wednesday and Amedy Coulibaly, the man who shot a policewoman and four hostages in a kosher supermarket in Paris last week before being killed in a shootout with French police.

French police had reported they were looking for accomplices of all three gunmen in the Paris attacks – Coulibaly, Saïd and Chérif Kouachi.

Riot police block the Rue de la Colline in Verviers, Belgium, during an anti-terrorist operation. Photograph: Olivier Hoslet/EPA

Belgium has a history in recent years as a European centre for radical Islamist activity. Authorities and studies by Britain’s International Centre for the Study of Radicalisation have estimated that about 300 Belgians have travelled to Syria, the highest per capita concentration in Europe for a country of 11 million. That compares with about 600 so-called foreign fighters who have left the UK.

One of Belgium’s best-known jihadist organisations – Sharia4Belgium – is at the heart of a huge, ongoing trial in Antwerp in which 46 members of the group have been accused of belonging to a terrorist organisation and brainwashing young men into fighting a holy war in Syria.

Last year, a gunman killed four people at the Jewish museum in Brussels. Belgian authorities say the suspect in that case, French national Mehdi Nemmouche, spent most of 2013 fighting in Syria.