The files cover criminal investigations during the 1954-1962 war of independence and are likely to confirm the widespread use of torture and extra-judicial killings by French forces.

"We have things to rebuild with Algeria. They can only be rebuilt on the truth," said Culture Minister Roselyne Bachelot on BFMTV.

"I want this question -- which is troubling, aggravating, and where falsifiers of history are at work -- I want us to be able to look it in the eyes. We can't build a national story on a lie," she added.

The announcement comes as France seeks to defuse a major diplomatic crisis between the two countries.

It was triggered in October when President Emmanuel Macron accused Algeria's "political-military system" of rewriting history and fomenting "hatred towards France".

- 'Never fear the truth' -

The trauma of the Algerian War has poisoned French politics for the past 60 years.

A key strand of today's far-right nationalism has its roots in the war and then-president Charles de Gaulle's abrupt decision to grant Algeria independence in 1962 -- for which he faced assassination bids and attempted military coups.

Asked about the likelihood that incidents of torture will be uncovered in the archives, Bachelot said: "It is in the interest of the country that they are recognised.

"We should never fear the truth. We must put it in context."

Historians have previously been able to request access to the archives, held in the southern city of Aix-en-Provence, but the procedure was lengthy and often blocked on national security grounds.

The declassification is not expected to include the army's files.

Macron, France's first leader born after the colonial era, has made a priority of reckoning with its past and forging a new relationship with former colonies.

He has recognised the killing of anti-colonial activists by French forces during the war, including Algerian lawyer Ali Boumendjel and communist activist Maurice Audin.

Macron also in October condemned "inexcusable crimes" during a 1961 crackdown against Algerian pro-independence protesters in Paris, during which police led by a former Nazi collaborator killed dozens of demonstrators and threw their bodies into the river Seine.

- No apology -

Karim Amellal, a scholar appointed as ambassador to the Mediterranean region by Macron, welcomed the move to open the files as "extremely positive".

"There is a very strong demand from historians to declassify documents covered by national security. We can't follow a policy of remembrance without following the path traced by these historians," he said.

Macron has, however, ruled out an official apology for France's actions -- seeing such a move as a gift to far-right opponents in next year's presidential election.

Meanwhile, his criticisms of the Algerian government in October have turned always-thorny relations into a full-blown crisis.

It did not help that Macron questioned whether Algeria had existed as a nation before the French invasion in the 1800s.

And it came just a month after France sharply reduced visa quotas for North African citizens.

Algeria has responded by withdrawing its ambassador and banning French military planes from its airspace, which they regularly use for anti-jihadist operations in the region.