The French government has threatened to punish active soldiers who signed an open letter by 25 retired generals warning President Emmanuel Macron the country is headed for "civil war".

A number of serving defence force members are believed to have signed the letter published last week in the right-wing Valeurs Actuelles magazine, which warned that "laxist" policies would result in chaos requiring "the intervention of our comrades on active duty in a perilous mission of protection of our civilizational values".

"The hour is grave, France is in peril," the retired generals wrote, adding that failure to act against the "suburban hordes" -- a reference to residents of the mainly immigrant areas that ring French cities -- and other unnamed groups who "scorn our country" will lead to "civil war" and deaths "in the thousands".

The government and left-wing parties strongly condemned the letter, which was published on the 60th anniversary of a failed coup d'etat by generals opposed to France granting independence to Algeria.

Christian Piquemal (R), retired general of the French Foreign Legion, is the lead signatory of a letter warning France's president of "civil war"
Christian Piquemal (R), retired general of the French Foreign Legion, is the lead signatory of a letter warning France's president of "civil war" AFP / DENIS CHARLET

It was not immediately clear from the list how many of the signatories, apart from the former generals, had retired from the defence forces and how many were still active members.

Defence Minister Florence Parly warned Monday that those still serving would be punished for flouting a law requiring them to remain politically neutral.

But she also appeared anxious to avoid giving too much importance to their outburst, assuring that the "immense majority" of French troops remained neutral and loyal.

Political analyst Jean-Yves Camus also downplayed the significance of the letter, telling AFP the signatories were "no heavyweights" in the army.

French far-right leader Marine Le Pen told the retired generals she shares their sentiment and invited them to back her campaign
French far-right leader Marine Le Pen told the retired generals she shares their sentiment and invited them to back her campaign AFP / Christophe ARCHAMBAULT

The letter comes as candidates begin jockeying for position on immigration, security and the spread of radical Islam in the run-up to the 2022 presidential election.

An Ifop poll published in the Journal du Dimanche newspaper on Sunday showed security and the fight against terrorism among voters' top priorities after a new wave of jihadist attacks, including the October 2020 beheading of a schoolteacher who showed his pupils cartoons of the Prophet Mohammed.

Far-right leader Marine Le Pen, whom polls show likely to face off against Emmanuel Macron next year in a re-run of the 2017 race, told the retired generals she shared their sentiments and invited them to back her campaign.

French Defence Minister Florence Parly has vowed to punish active soldiers who signed an open letter warning the country is headed to "civil war"
French Defence Minister Florence Parly has vowed to punish active soldiers who signed an open letter warning the country is headed to "civil war" AFP / Fabrice COFFRINI

"I invite you to join us in taking part in the coming battle, which is the battle of France," she wrote in a response to the letter published in Valeurs Actuelles.

Le Pen was widely criticized by her opponents on both the left and the right for her overtures to the soldiers behind what the left-wing daily Liberation described as a "call to sedition".

On Tuesday, she told France Info that while she shared the soldiers' diagnosis of a country afflicted by "lawless areas, crime, self-hatred and our leaders' rejection of patriotism" she agreed that "these problems can only be solved by politics."

The public foray by the generals, most of whom are close to far-right circles according to France Info, comes in the midst of a heated debate in France about racism and colonialism led by young, non-white French activists.

The generals accused them of whipping up "hatred between communities" with their rhetoric and support for tearing down statues of French figures from colonial times.

Macron, who was elected on a centrist manifesto in 2017 but is seen by critics as moving to the right, has slammed what he calls "social science theories imported from the United States", saying that they harm French unity.

The generals also accused "Islamism and the suburban hordes" of turning parts of the country into no-go areas where French values were no longer upheld.

"Who could have imagined 10 years ago that a teacher would one day be beheaded on leaving school," they wrote referring to the murder of Samuel Paty by a radicalised Chechen immigrant, a crime that caused deep shock in France.

While extremely rare, this is not the first time that former military top brass have criticised the running of the country.

A popular former head of the armed forces who quit after a spat with Macron in 2017, General Pierre de Villiers, has been cited as a possible presidential candidate after publishing a book on "repairing France."

The lead signatory of the letter in Valeurs Actuelles, Christian Piquemal, is a former Foreign Legion commander who was arrested for taking part in an anti-migrant demonstration in 2016.