By Dominique Vidalon and Clotaire Achi
PARIS, Nov 5 (Reuters) - Flag-waving protesters marched through French cities and public workers went on strike on Thursday, in a renewed challenge to President Emmanuel Macron after weeks of unrest that have rattled his government five months before a presidential election.
The mobilisation, called by trade unions including the left-wing CGT and backed by student groups, comes after demonstrations over living costs, public services and education triggered the worst civil unrest France has seen in years.
"We need to turn up in big numbers on the streets today," CGT head Sophie Binet told LCI TV, saying protests were planned in 260 towns and cities across France.
French high school students and other demonstrators faced off against riot police in Paris as they blocked a street with rubbish bins on Thursday morning.
Demonstrations began in the southern cities of Marseille and Lyon and in Nantes in the west in mid-morning. The main protest in Paris was scheduled to start from Place de la Republique at 2 p.m. (1300 GMT).
"High school students, pensioners, students, workers, all together. Unity wins," read one banner prepared for the protest in Lyon.
Some of those gathering in Lyon carried face masks or safety glasses as a precaution against the use of tear gas by police.
Authorities have sought to lower tensions after riots and looting on October 17 caught security forces off guard, leaving damaged shops and public buildings across the country and fuelling criticism of Macron's handling of the crisis.
French authorities will deploy around 70,000 police nationwide. The domestic intelligence service expects between 500,000 and 700,000 people to join demonstrations outside Paris.
The strike had already contributed to a reduction in France's nuclear output early on Thursday. However, no major problems were reported on the transport network.
STUDENTS AIR GRIEVANCES
The Education Ministry said it expected 17.5% of public primary school teachers to strike.
Students say conditions in schools and growing uncertainty over their future remain major concerns.
"We're trying to keep mobilising as much as possible. Some people aren't doing so because they're afraid. A lot of people are afraid of police violence," said Irma de Banville, a 19-year-old student in Paris.
The French government has defended police tactics while saying any abuses would be investigated.
Macron convened a defence and security meeting on Wednesday ahead of the protests, underlining how a movement that began with student anger over deteriorating school conditions and concerns about opportunities for young people has evolved into a broader challenge to his government.
"The goal in the coming weeks is to get the river that overflowed back into its bed and to launch the presidential election in the calmest possible conditions," an official close to Macron said, pointing to the lower number of high schools blockaded this week compared with earlier in the crisis.
Nationwide protests last Saturday were generally peaceful, with some clashes on the fringes. Even so, the political atmosphere remains tense, with candidates manoeuvring ahead of the election and opposition parties seeking to capitalise on public frustration over living standards and government policy.
(Additional reporting by Forrest Crelin; writing by Michel Rose and Keith Weir; editing by Gareth Jones)
