Paris police have fired tear gas on a group of yellow-vested protesters trying to march on the French presidential palace and are pushing them back with shields.
Crowds of protesters first tried to march down the Champs-Elysees avenue toward the Elysee palace but were prevented by rows of police. So a group of a few hundred took side streets and tried to get past a police barricade, and police fired back with tear gas.
Most of the protesters remain peaceful, and there are no signs so far of the rioting and looting that marked a similar protest last Saturday and prompted fears of greater violence this week.
Crowds were also gathering across town around the Bastille plaza.
Authorities have detained 343 people already Saturday amid exceptional security and filtration measures.
Police are searching people throughout zones of central Paris and confiscating goggles and gas masks from journalists who use them to protect against tear gas while covering demonstrations.
A crowd of "yellow vest" protesters is marching down the Champs-Elysees avenue in central Paris surrounded by exceptional police security amid fears of new violence.
Hundreds of people gathered early Saturday around the Arc de Triomphe, which was damaged in rioting a week ago. They then started walking peacefully down the avenue, lined with high-end shops normally bustling before the Christmas holidays but boarded up this Saturday amid worries of more looting or other damage.
A Paris police spokesman said more than 170 people have already been detained Saturday on suspicion they were planning violence, though most were later released.
President Emmanuel Macron's government is deploying 89,000 security forces around the country for Saturday's protests against his reforms.
The French yellow vest protest movement is crossing borders, with demonstrations planned in neighboring Belgium and in the Netherlands.
Neither country has proposed a hike in fuel tax - the catalyst for the massive and destructive demonstrations in France in recent weeks.
Hundreds of police officers are being mobilized in Brussels Saturday, where yellow vest protesters last week clashed with police and torched two police vehicles. More than 70 people were detained.
Some rallies are taking place outside the main European Union institutions, which are closed Saturdays. Some could be held in the city center on what is a major Christmas shopping weekend.
Jan Dijkgraaf, editor of a Dutch "resistance newspaper" is calling for peaceful protests in the Dutch cities of Amsterdam and Rotterdam.
Paris monuments and shopping meccas are locked down and tens of thousands of police are taking position around the country, fearing worsening violence in a new round of anti-government protests.
President Emmanuel Macron's government has warned that Saturday's "yellow vest" protests in Paris will be hijacked by "radicalized and rebellious" crowds and become the most dangerous yet after three weeks of demonstrations.
Authorities are deploying barricade-busting armored vehicles and 8,000 police in the capital alone, part of 89,000 security forces fanned out around France.
The Eiffel Tower and Louvre are shut along with hundreds of stores and businesses, fearing damage after rioting last Saturday that saw 130 people injured and the worst urban unrest in Paris in decades.
The protesters are angry at Macron and high taxes, among other problems.