AJACCIO, France, Feb 3 (Reuters) - Thousands of Corsicans marched in Ajaccio, the French Mediterranean island's capital, on Saturday to demand more autonomy, ahead of a visit by President Emmanuel Macron next week.

An alliance of Corsica's two main nationalist parties, helped by disillusion with mainstream parties tarnished by corruption, swept to victory in a local election on Dec. 10 and has been pressing for talks with Paris.

Its leaders want more autonomy on fiscal issues, equal status for the French and Corsican languages, and the limiting of the right to buy property in some areas to people who have been resident on the island for at least five years.

The local prefecture said between 5,600 and 6,000 people marched peacefully in Ajaccio, while organisers put the number of protesters at between 22,000 and 25,000.

"It's a historic moment, a march of unprecedented proportions in Ajaccio," the island's chief Gilles Simeoni told reporters.

Macron's government has said it is open to some changes in its relationship with Corsica.

But ministers have rejected some demands, such as the language question, which would require changes to the French constitution which states that French is the Republic's sole official language.

That has infuriated nationalist leaders, who had urged Corsicans to join the protest march, ahead of Macron's visit on Tuesday.

The government is playing with fire by rejecting the nationalists' demands, Simeoni told Reuters in an interview this week, alluding to the independence movement's violent past.

Before laying down arms in 2014, groups backing Corsican independence had carried out more than 10,000 attacks over four decades, blowing up police stations and holiday homes.

These clandestine groups were linked to at least 40 deaths, either in attacks on government officials or as a result of infighting among rival factions.

Corsica has 325,000 inhabitants and accounts for less than 0.5 percent of France's economy. (Reporting by Paul Ortoli in Ajaccio; Writing by Michel Rose in Paris; Editing by Andrew Bolton)

Our Standards: The Thomson Reuters Trust Principles.