In all five people were arrested during the raids carried out overnight on July 4th, one in northern France and four others in Belgium. They were linked to a radicalized bikers’ club known as the Kamikaze Riders, which has been implicated in terror offences.

Police also discovered an arms cache including Kalashnikovs, handguns and a rifle. Police uniforms were also found.

Although police are not yet aware of any specific plot for a certain date, French authorities – fearing a repeat of last year's Bastille Day terror attack in Nice when a jihadist drove a truck into crowds along the beachfront killing 86 – did not want to take any chances.

“This is a group we have been following for quite some time,” a Belgian police source told L’Express newspaper. “The arrests were carried out at the behest of France, but not because we had knowledge of a specific target.”

“With July 14th approaching, the French did not want to take any risks,” the source said.

It has emerged that 42-year-old man arrested in a suburb of the northern city of Lille is suspected of supplying arms to those arrested in Belgium after he was spotted carrying a bag to a garage in a suburb of the gritty city of Anderlecht, that was rented by two brothers who were suspected members of the Kamikaze riders.

Police in Belgium are still hunting several suspects who were not picked up in this week’s raids. 

Brussels has been on high alert since Islamic State suicide bombers struck the city's airport and metro in March 2016, killing 32 people and injuring hundreds more.

France, also on high alert for terrorist attacks, voted on Thursday to extend its state of emergency for one last time.

The emergency measures, brought in after the November 2015 terror attacks in Paris, will run until November 1st after which the government hopes to replace it will a new law aimed at countering the terror threat.

France's Interior Minister Gerrard Collomb said this week that French police and intelligence services had thwarted seven attacks since the beginning of the year.