French President Francois Hollande Monday denounced the killing of two policewomen as an "attack" on the nation as officials said a young mason arrested had confessed to the crime.

The gendarmes, aged 29 and 35, were shot dead with the service pistol of one of them in the southeastern village of Collobrieres as they investigated a petty theft, investigators said.

"It's a tragedy... it's the Republic which has been attacked," Hollande said in a statement as the killings sent shockwaves across the country, adding: "I learnt of the deaths with great sadness."

The man was arrested early Monday near Collobrieres after a massive manhunt involving more than 300 men, including a special operations military unit, and a helicopter.

The 30-year-old confessed, Toulon prosecutor Xavier Tarabeux told a news conference, adding that he had emerged from jail in September after a six-year stint in prison.

His previous run-ins with the law revolved around drug trafficking and robbery with violence. Only a week earlier he was put on probation for attacking his mother.

A police spokesman for the local Paca region said the force was "deeply shocked." The elder victim, Audrey Berthaut, had two daughters aged five and 13 while the other, Alicia Champlon, was another gendarme's partner.

Interior Minister Manuel Valls, designated by Hollande to go to Collobrieres as the president had to head off to Mexico for a G20 summit, said the killing had sparked "shock in the village and in the police force."

Valls laid a wreath at the site said the nation would in "the coming days pay homage to these two policewomen."

The mason, who was seen drunk in public on Sunday evening, was suspected by a local woman of stealing her handbag.

Her husband went to his house and there was a heated argument. The two policewomen arrived and the suspect beat and kicked Berthaut, a senior NCO, in the head before shooting her twice with her Sig Sauber 9 mm calibre pistol, officials said.

Champlon tried to get away and he fired six shots at her before fleeing along with his girlfriend, only to be arrested a few hours later.

Police unions on Monday denounced the "cowardly" murder and called for "maximum punishment for cop killers."