PARIS (Reuters) - France will build thousands of new jail cells and use electronic tagging more widely under reforms being pursued by President Emmanuel Macron to remedy some of the worst prison overcrowding in Europe and protests by wardens over violence.

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France's prison population of 69,000 is the fifth-largest in Europe, after Russia, Turkey, Poland and Britain, World Prison Brief data compiled by a London university shows. (bit.ly/2HbnkVC)

But French jails are more overcrowded than those in Britain, with an average 115 inmates per 100 places. In some Paris area jails there are reports of inmates sleeping on floors with three or more prisoners squeezed into a cell.

To address that, Macron pledged to promote outside-of-prison alternatives for lesser offenders.

“Prison sentences are not there to respond to society’s emotions,” Macron said, warning that prison sometimes created “monsters”. “A convicted individual is meant to return to society.”

Prison sentences of less than a month will be banned, the 40-year-old president, elected in May last year, said. Those between one and six months will be mostly served at home with electronic tagging, thus shrinking jail capacity needs.

Drug use will be punished with fines rather than prison time, he added.

However, it was only technically possible to add 7,000 news cells over the time of his mandate to tackle overcrowding, he said, less than the 15,000 he promised during his campaign.

The changes, presented by Macron during a visit to southeast France on Tuesday, follow a rash of attacks by inmates that triggered protests by guards, who said violence was spinning out of control.

The protests eased when the government offered 30 million euros for better training and pay, as well as moves to isolate Islamist militants from other prisoners. With his latest announcement, Macron is promising to go further..

Government spokesman Benjamin Griveaux said about one in three prisoners are behind bars for less than a year -- some of whom could benefit from alternatives to incarceration.

“For many of these people, going to prison is the best way to ensure they become repeat offenders,” he told RMC radio.

Griveaux described the current system as incomprehensible, not least because first-time offenders who receive sentences of less than two years very rarely actually go to prison -- a custom Macron says he will end.

“Nobody understands how things work anymore,” Griveaux said.

Britain and the United States, the country with the world’s largest prisoner population, have increasingly resorted to the privatization of prisons and correctional facilities to lower costs and improve efficiency.

Macron did not venture an opinion on the subject.