France's government will cut 7,500 fewer jobs in the military than first planned to better fight terrorism in the wake of the Paris attacks.

After President Francois Hollande met on Wednesday with his top security advisers, his office said in a statement that a five-year military development budget programme would cut 18,300 positions through 2019 instead of 25,800.

Long before the attacks this month in Paris, the cost-cutting French government had approved the military job cuts as a way to reduce the country's expanding budget deficit.

The cuts are to be completed by summer.

Authorities have deployed more than 10,000 extra troops across France since the January 7-9 attacks on the Charlie Hebdo satirical newspaper and a Jewish supermarket.

The Socialist-run government also announced new security measures on Wednesday, including equipping security forces better and hiring 2,680 counterterrorism officers, just under half of them in the intelligence services.

Meanwhile, France has started to issue first charges over Paris attacks that left 20 people dead, including three assailants, earlier this month.

Earlier on Wednesday, Francois Molins, Paris prosecutor, said that four men aged between 22 and 28 were handed preliminary charges of association with terrorism.

Three of them are suspected of having bought "equipment" for Amedy Coulibaly, who shot a policewoman to death on the outskirts of Paris and then killed four hostages at a kosher supermarket.

The prosecutor said the four charged suspects were jailed until a further investigation.

Three of the four had criminal records and at least one met Coulibaly in prison, Molins said.

He said that authorities in France are working with other countries to search for other possible accomplices.

Molins said investigators were trying to uncover who was responsible for the posthumous video of Coulibaly, which was edited and released days after he and the Charlie Hebdo gunmen Said and Cherif Kouachi were killed by police.

In the video, Coulibaly pledges allegiance to the Islamic State of Iraq and the Levant (ISIL) group and details how the attacks were coordinated by the three men.