INTERNATIONAL: French security forces briefly fired tear gas in Paris as opponents of the far-right marched in the capital on Saturday 16th April. Then the demonstrators resumed their protests minutes later.

Thousands of anti-far right protesters marched across France on Saturday as opponents of presidential candidate Marine Le Pen seek to form a united front to prevent her from winning an election runoff against incumbent Emmanuel Macron on April 24.

Police have warned of possible incidents as demonstrators convene in some 30 cities.

Macron, a pro-European Union centrist, won the presidency in 2017 after easily beating Le Pen when voters rallied behind him in the runoff to keep her far-right party out of power.

This year, the first round of voting last Sunday set up the same battle, but Macron is facing a much tougher challenge.

"The far-right is a risk to our country," he told supporters overlooking the Mediterranean port city, which put far-left candidate Jean-Luc Melenchon first on April 10. "Don't heckle them! Beat them!," he said.

Prior to the first round of the election Le Pen successfully tapped into anger over the cost of living and a perception that Macron is disconnected from everyday hardships. That saw her finish with 23.1% of votes compared to 27.85% for Macron.

However, she has appeared more rattled this week as the focus has turned to her manifesto and opinion polls have shown Macron extends his lead. A poll on Saturday showed the president winning the runoff with 55.5% of votes.