Police officers patrol at Charles de Gaulle airport in Paris, capital of France, March 22, 2016. (Xinhua/Theo Duval)

PARIS, April 18 (Xinhua) -- Two men were arrested on Tuesday in Marseille on suspicions of preparing an "imminent, certain" attack on French soil, "in the coming days," French Interior Minister Matthias Fekl said.

French police held earlier on Tuesday morning two individuals "on suspicion of planning violent act on the eve of presidential election," Fekl said.

The two French nationals, aged 23 and 29, were known to intelligence services for radicalization, he added.

An ongoing search operation in a building located in the third district of Marseille has so far uncovered materials on the planned attack, according to the minister.

Reiterating the government's "relentless fight against terrorism," Fekl pledged that "every effort is made to ensure the security of the presidential election."

A total of 50,000 policemen and gendarmes will be mobilized during the two rounds of presidential elections on April 23 and May 7.

France remains in a state of emergency and on high alert over possible terrorist attacks.