France will be on extra high alert on Monday as union members and protesters march against Marine Le Pen while her Front National party holds its annual gathering to honour Joan of Arc.

As the FN pays tribute to the nationalist icon, union leaders and left-wingers have called for a massive turnout for traditional May Day marches through Paris as a show of strength against the far-Right presidential contender.

More than 9,000 armed police and soldiers will try to keep the two sides apart. Up to 250 May Day events are planned across the country amid fears of an attack similar to the Champs-Elysées killing of a policeman earlier this month, days before the first round of the presidential election.

France remains under a state of emergency introduced after the November 2015 Paris attacks. Political tensions are rising in the run up to the final round of the election on Sunday, in which Emmanuel Macron, a centrist, is expected to beat Ms Le Pen.

Her father, Jean-Marie Le Pen, who founded the FN, will lay a wreath at a statue of Joan of Arc in Paris and supporters will march to another location where he will deliver a speech.