French President Francois Hollande on Monday denounced an arson attack on a mosque in the city of Auch in southwestern France.
Hollande said in a statement that he “strongly condemns this act which undermines the values of our Republic and respect for beliefs” after an investigation found that the incident was planned.
“Muslims in France should be able to practice their religion freely and safely, everything is being done to ensure that the perpetrators are identified and punished,” he stressed.
Around 70 percent of the Salame D'Auch Mosque in Auch, near Toulouse, burned down over the weekend.
While no one was injured in the blaze, flames gutted the building and destroyed two prayer rooms and large parts of the roof.
By Monday investigators found that the fire was lit deliberately, confirming the suspicions of firefighters at the scene who said that there was a strong smell of gasoline in the building at the time.
The arson attack on the mosque came after a gunman armed with an automatic rifle and a box cutter attacked a train from Amsterdam to Paris on Friday.
The incident left three people injured, including one of the men who subdued the gunman - a 26-year-old of Moroccan origin who was known to the intelligence services - French investigators said.
Mosques in France and several other European countries have become targeted by extremist groups after terror attacks in public places.
French mosques were also attacked after the killing of 12 people at the office of the French satirical magazine Charlie Hebdo.
According to statistics gathered by the National Islamophobia Observatory 147 acts of violence were committed against Muslims or Muslim places of worship between January 7 and the end of the month following the Charlie Hebdo attack.
These included physical attacks on 26 mosques around the country, some of which involved the use of firebombs.
The growth of France's Muslim population has led to discussions about what impact this might have, if any, on France's secular traditions.
The French government banned head scarves and other religious symbols from public schools in 2004.