The planned attacks were imminent, they said, adding that two suspects shot dead in Verviers during the raids were still being identified.

Searches were also carried out overnight in the Brussels area.

Thirteen suspects had been arrested, while two were arrested in France.

Guns, munitions and explosives, as well as police uniforms and a large amount of money, were seized during the raids, prosecution spokesman Thierry Werts told reporters.

Eric Van Der Sypt, another spokesman, added: “The investigation… has shown that these people had the intention to kill several policemen in the street and at police commissariats [police stations].

“The operation was meant to dismantle a terrorist cell… but also the logistics network behind it,” he said.

No link had been established with last week’s attacks in Paris, Mr Van Der Sypt said, adding that Belgium would seek the extradition of the two suspects in France.

“I can confirm that we started this investigation before the attacks in Paris,” he said.

Last week, gunmen in Paris attacked the offices of satirical magazine Charlie Hebdo, a kosher supermarket and police officers, killing 17 people in the French capital.