The French government will unveil Thursday an overhaul of the country's labour code -- a collection of laws setting out workers' rights spanning over 3,000 pages, some dating back over a century.

The reforms are the biggest -- and riskiest -- of Emmanuel Macron's young presidency. 

The 39-year-old centrist believes that making the labour market more flexible will help drive down unemployment of 9.5 percent, but leftists fear an erosion of workers' rights.

- What's going to change? - 

The broad thrust of the reforms was discussed during several rounds of meetings with employers and trade unions, but much of the detail will be revealed for the first time Thursday. 

Macron wants to cap the compensation awarded by labour courts in cases of unfair dismissal -- a demand of bosses who complain that lengthy and costly court cases discourage them from hiring.

He also wants to give employers more freedom to negotiate terms and conditions with employees at the company level, rather than being bound by industry-wide collective agreements.

Other measures include streamlining workers' committees, which are mandatory within large companies, and expanding the use of flexible "project contracts".

In a further concession to companies, multinationals whose French operations are struggling will find it easier to lay off staff, while redundant workers will receive higher payouts.

Several issues are still in contention, with the government set to act as final arbiter.

- What do the unions say ? - 

The hardline CGT union -- the biggest in the country -- has accused the government of "social regression" and called a day of nationwide strikes and protests for September 12, along with the smaller CFE-CGC union.

But more moderate unions, including the CFDT -- the biggest private-sector union -- have adopted a wait-and-see approach.

In parliament, the opposition to the changes is being led by the radical France Unbowed of leftist firebrand Jean-Luc Melenchon, which is planning a mass march in Paris on September 23.

The right and centre-left have broadly backed the reforms.

- What's at stake for Macron? -

The reforms will test Macron's reformist zeal. He cleared a first hurdle this summer when parliament adopted a law allowing him to implement the reforms by decree, but has yet to win over the street.

Macron is hoping to avoid a repeat of the months-long, sometimes violent protests unleashed by labour reforms pushed through last year by his predecessor Francois Hollande.

Divisions in the trade union movement have strengthened his hand.

It remains to be seen if his opponents are able to mobilise in the numbers seen last year against Hollande, but few see them capable of repeating the stoppages and protests against pension reform in 1995 and 2010.