“My client cooperated,” said the man’s lawyer, Quentin Chabert, to the Presse-Océan newspaper, without specifying the reasons for the attempt to burn down the Saint-Pierre and Saint-Paul cathedral.
“He bitterly regrets his actions… My client is consumed with remorse,” said Chabert.
Prosecutors have opened an arson investigation following the morning fire of July 18, after finding that it had erupted in three different locations in the church, which the volunteer had locked up the night before.
He was interrogated the next day, then released without charge, the rector of the cathedral saying: “I trust him as I trust all in attendance.
But Nantes prosecutor Pierre Sennes said in a statement on Saturday that the man had been charged with “destruction and damage by fire”, and faces up to 10 years in prison and 150,000 euros (£ 136,000) fine.
“He admitted in his first appearance for questioning before the investigating judge that he had lit three lights in the cathedral: the main organ, the smaller organ and the electrical panel,” said Sennes.
The blaze came 15 months after the devastating fire at Notre Dame Cathedral in Paris, which raised questions about the security risks of other historic churches across France.
While firefighters were able to contain the Nantes blaze after just two hours and save its main structure, the famous organ, which dated from 1621 and had survived the French Revolution and WWII bombing, was destroyed.
Priceless artifacts and paintings have also been lost, including a work by 19th-century artist Jean-Hippolyte Flandrin and stained-glass windows containing remains of 16th-century glass.
Work on the cathedral began in 1434 and continued over the following centuries until 1891.
It had already been damaged by a more serious fire in 1972, when authorities added concrete reinforcement while re-roofing over the next 13 years.
The French government has said it will ensure the restoration of the cathedral. Philippe Charron, head of the DRAC’s regional heritage agency, said very few, if any, parts of the main body were likely to be saved.
“It will take several weeks to secure the site… and several months of inspections which will be carried out stone by stone,” he said. He added that the reconstruction would take several years.