Marine Le Pen accused Emmanuel Macron of being "weak" over Islamist terrorism on Monday as aides slammed him as "arrogant" for holding a glitzy party in a high-end bistro "as if he'd already won", a day after the pair reached the second round runoff on May 7.

The blistering attack from the far-Right Front National candidate came hours after she won 21.4 per cent of the national vote, just behind Mr Macron, an independent centrist, who came top on 23.9 per cent.

For the first time in almost 60 years, neither the mainstream Left nor Right managed to reach the final.

While polls suggest Mr Macron will trounce Ms Le Pen in the runoff, Sunday's first round vote split France down the middle both politically and geographically; the electoral map shows the centrist came top in the West while the FN leader triumphed in the East.