Protesters held banners saying: "Stop the plunge in our purchasing power"
Violence has flared on the French Indian Ocean island of Reunion during demonstrations against high prices.
Police fired tear gas to disperse stone-throwing youths at a protest near Reunion's capital, Saint-Denis.
Thousands marched across the island to push for a 20% cut in the prices of essential goods and an extra 200 euros (£178) a month for low-paid workers.
The unrest came after unions on the French Caribbean island of Guadeloupe had agreed to end a 44-day strike.
The LKP collective signed a deal with officials and business owners to raise workers' pay and lower the cost of basic goods. Negotiations are continuing in nearby Martinique over a similar stoppage.
On Reunion, an island of about 800,000 people east of Madagascar, unions said their members would go on strike next Tuesday unless their demands were met.
As in the French Caribbean, union members complain that prices are considerably higher than in mainland France, and that their salaries have not kept pace with them.
The overseas territories have the highest unemployment rates in France.
In the French Caribbean, some residents alleged that a wealthy, white elite was controlling imports and prices.
Hundreds of police and gendarmes have been deployed from France in recent weeks to help restore order. Dozens of protesters have been arrested since the strikes began.
Wednesday's agreement in Guadeloupe covered a wide range of issues, including the price of bread, the hiring of teachers and reduced air fares. But most importantly, it will see the wages of the lowest-paid workers supplemented with a 200-euro monthly payment.