Police have used water cannons and tear gas on several hundred hooded youths who joined a protest march in Paris against French President Emmanuel Macron's pro-business labour policies.

The youths who showed up near the end of the march pelted security forces with objects, briefly halting the event held by unions and other groups.

While union marches are usually peaceful, troublemakers on the margins often clash with police.

The CGT union, which organised marches around France, said 60,000 people participated in the Paris protest.

Police put the figure at 24,000. A statement said four people were detained and one person with a minor injury was taken to hospital.

The protests are the first big public display of discontent with Mr Macron's presidency, which kicked off in May amid enthusiasm over his promises of revving up the French economy but is now foundering amid anger over the labour decrees and other domestic troubles.

Thousands of union activists marched this morning in the Mediterranean city of Marseille, in Le Havre on the English Channel and other cities.