Belgian police have arrested 13 people during a dozen raids overnight, halting an alleged plot to kill police officers "in public roads and in police stations," prosecutors said.
Two suspects were shot dead during a gun battle after one of the police raids in the eastern town of Verviers on Thursday night. Local media reports said there were no casualties among the security forces involved.
Police found Kalashnikov assault rifles, explosives, ammunition and communication equipment — along with police uniforms that could have been used for the plot, said Belgian federal magistrate Eric van der Sijpt during a Friday news conference.
Belgium will seek the extradition of two Belgian suspects from France, although prosecutors said they have found no link between the planned attacks in Belgium and last week's shootings in Paris.
"I can confirm that we started this investigation before the attacks in Paris," van der Sijpt said. The "important arrests" meant that "not only a terror cell but also their support network" have been dismantled.
France's Prime Minister Manuel Valls confirmed that there was no "direct link" between the raids in Belgium and last week's attacks in Paris.
Some of the suspects recently returned from Syria. Per capita, more people from Belgium, with a population of 11.2 million, have taken part in the fighting in Syria than from any other European state. The Belgian government believes that about 100 of its nationals have returned with combat experience. A further 40 may have been killed, and about 170 are still in the ranks of fighters in Syria and Iraq.
Belgian security forces were on high alert Friday, with extra armed security in evidence at some public buildings, notably police stations. Public broadcaster RTBF said officers were told not to be on the streets alone while in uniform.
Some Jewish schools in Belgium and the Netherlands were closed, reflecting the heightening of an atmosphere of caution that has prevailed across Europe since three gunmen killed 17 people in Paris last week at a Jewish grocery and the offices of the satirical French newspaper Charlie Hebdo.
In Germany, 250 police officers conducted raids of at least 11 residences in Berlin and took two men into custody on suspicion of recruiting fighters and procuring equipment and funding the Islamic State in Iraq and the Levant.
Al Jazeera and wire services