The two men suspected of plotting an "imminent" attack ahead of

The foiled plot in Marseille sparked fears that the closing days of the campaign could be a target for extremists ahead of Sunday's first round of voting in the country's most unpredictable election in decades.

Elite police and intelligence agents arrested the two Frenchmen -- 23-year-old Clement Baur and Mahiedine Merabet, 29 -- on Tuesday in the Mediterranean port city.

Paris prosecutors said the men are accused of participating in a terrorist conspiracy as well as weapons charges.

After searching the suspects' shared Marseille apartment, authorities said they uncovered an Uzi sub-machine gun, pistols, three kilogrammes (6.5 pounds) of TATP explosives and a homemade grenade as well as an Islamic State group flag.

Police had been searching for them since April 12 following the interception of a video in which they pledged allegiance to IS.

The men had used a number of aliases, switched mobile phones frequently and used pre-paid bank cards to evade police.

Two days after the arrests, 39-year-old Karim Cheurfi shot dead a policeman on Paris's Champs Elysees avenue before being killed by police gunfire.

A note praising the Islamic State group was found near his body.

More than 230 people have been killed in a string of jihadist attacks in France since January 2015.