"Those who want to leave can do so but they need to do it now," she told followers at a meeting of European far-right leaders in Madrid.

"Having people here while their heart or their mind is elsewhere is unbearable.

"It is a total lack of dignity and respect towards all of our supporters."

It comes as her niece voiced approval for Ms Le Pen's rival Eric Zemmour, saying he was a better candidate for the country's presidential election.

Her niece, Marion Marechal, made the comments in an interview with French newspaper Le Parisien, saying her aunt showed a "lack of logic and vision".

Ms Marechal is herself a popular figure among far-right voters, and an ideological divide between the two has been speculated about for years.

She is reportedly considering joining Mr Zemmour's party, which holds more extreme views on issues like immigration.

Ms Le Pen's party National Rally - formerly National Front - had already suffered the defection of two EU lawmakers.

A tussle on the far-right

Ms Le Pen is placing second or third in opinion polls, as both her and Mr Zemmour battle for the support of nationalist voters in a bid to face current president, Emmanuel Macron, in the next round.

Her father led National Rally for years until she took over in 2011, with the party dominating far-right politics for decades, but it has failed to achieve major electoral success.

Ms Le Pen will be hoping to improve on regional election results last year, which saw her party fail to win any of mainland France's 12 regions.

Mr Zemmour, a far-right TV pundit, entered the race in November, and has since voiced anti-Islam and anti-migrant views.

This month, he was fined €10,000 (£8,350) for hate speech over remarks made on a right-wing TV channel in which he called young migrants killers, thieves and rapists in 2020.

He said he would appeal the decision.

European Parliament member Gilbert Collard joined Mr Zemmour's Reconquest party from National Rally in a sign the TV pundit's entrance into the race could split the hard-right vote, with more extreme voters attracted to his radical views.

Macron likely to seek re-election

Mr Macron is leading polls, however, and is expected to win the 2022 election comfortably.

This is despite also performing poorly in the country's regional elections with the ruling Republique en Marche party failing to win a single region outright.

Most candidates voiced frustration at low turnout, with only 33% of France's voting population taking part.

The incumbent is yet to formally confirm he will seek re-election with the announcement expected soon.

This year, protests broke out when Mr Macron said he wanted to "p*** off" people who had not been vaccinated against COVID-19.

The French parliamentary elections will also be held this year, when the leaders of the country's political parties will again fight for seats.