In France, workers and unions opposed to the government's pension reform went to protest on May 1, International Workers' Day.
Workers began to gather in the French cities of Nantes, Lyon, Marseille and Strasbourg at a large rally that started in the afternoon in Paris.
The French Interior Ministry will deploy 12,000 policemen across the country, including 5,000 in Paris, as authorities expect up to 650,000 protesters in 380 rallies in a single day, Le Figaro said in a news report.
Interior Minister Gerald Darmanin also expressed support for the use of drones for surveillance purposes in a text message sent to local authorities, the daily reported, citing a source.
Flights were canceled after airline workers decided to strike on Monday.
A third of the flights were canceled at Paris-Orly, Marseille, Lyon, Bordeaux, Nantes, and Toulouse airports, while 25% were canceled at Paris Charles-de-Gaulle and Nice airports.
Protests have continued unabated since January.