What happened today in France's presidential race

Marine Le Pen, the French presidential election candidate for the far-right National Front

With two weeks to go before the first vote in France's rollercoaster presidential election, protesters disrupted a rally by far-right leader Marine Le Pen, while a poll showed the gap between the top four candidates narrowing.

Here's what happened in the campaign on Saturday:

- Scuffles at Le Pen rally -

Scuffles broke out in a meeting room where Le Pen was due to speak on the island of Corsica, after security staff from her National Front (FN) party tried to eject around two dozen young Corsican nationalist protesters.

An FN security officer set off tear gas as punches were thrown, forcing staff to evacuate the room. Le Pen eventually had to hold the rally at a different location in Ajaccio, the capital of the Mediterranean island just off the coast of Italy.

Le Pen blamed local prefect Bernard Schmeltz for the violence, charging that he had "escorted these violent activists right up to the door of my meeting", and denying that her staff bore any responsibility. Schmerz said security around the event had been entirely proper.

The protesters had shouted "a Francia fora" ("France get out" in Corsican) and the separatist group Ghjuventu Indipendentista claimed responsibility for the disruption on Twitter.

"We can't accept the National Front candidate coming to our territory to spread her message, which is stamped with the seal of hate and straightforward anti-Corsicanism," the group wrote.

The National Liberation Front of Corsica (FNLC) ran a brutal campaign of bombings and assassinations from 1976 to 2014. But today's nationalists are trying a peaceful approach to power, having performed strongly in regional elections in 2015.

- Race tightens at top -

Several opinion polls show a tightening race between the top four candidates, with support for frontrunners Le Pen and centrist Emmanuel Macron slipping back and conservative Francois Fillon neck-and-neck with Jean-Luc Melenchon of the far-left.

A poll by BVA Salesforce showed acid-tongued Melenchon jumping by four points in a week to 19 percent of first-round voting intentions -- the same as Fillon, who was once considered the favourite but has seen his ratings hit by a string of expenses scandals.

Ahead of the first round on April 23, Macron and Le Pen both hold 23 percent of voting intentions, according to the poll -- just four points ahead of their other two rivals in one of the most unpredictable French elections in decades.

- Socialists called to order -

The ethics authority of the bitterly divided Socialists called the party to order, deploring members who have declined to back their struggling candidate Benoit Hamon.

Former premier Manuel Valls is among senior Socialists who have opted instead to back Macron -- an attitude the ethics office criticised as contrary to "the principle of loyalty" and disrespectful of the public primary that saw Hamon emerge as candidate.

The BVA poll credited Hamon with just 8.5 percent of voting intentions, with both Macron and Melenchon having sapped his support.