France’s far-right party leader Marine Le Pen has paid tribute to the man who killed himself in the Notre-Dame de Paris cathedral, saying it was a “political act”.
Ms Le Pen, who heads the National Front, said it was aimed at “waking up the people of France”.
The man was named as Dominique Venner, an award-winning far-right historian.
In his blog written shortly before his suicide on Tuesday, he criticised a new law legalising gay marriage.
“All respect to Dominique Venner whose final, eminently political act was to try to wake up the people of France,” Ms Le Pen wrote on Twitter.
She later added that “it is in life and hope that France will renew and save itself”.
Bruno Gollnisch, another National Front member, said that Mr Venner’s “dramatic act was a protest against the decay of our society”, according to the AFP news agency.
Mr Venner, 78, pulled out a shotgun and shot himself through the mouth beside the main altar shortly after 16:00 (14:00 GMT) on Tuesday – in front of some 1,500 visitors at the cathedral.
The police said he had made no statement before killing himself, although a note was found next to his body. They did not disclose its contents.
Just hours earlier, Mr Venner wrote on his blog a damning critique of the same-sex marriage bill.
“New spectacular and symbolic actions are needed to wake up the sleepwalkers and shake the anaesthetised consciousness.
“We are entering a time when acts must follow words.”
Mr Venner was also a former member of the Secret Army Organisation (OAS), which opposed Algerian independence in the early 1960s and tried to assassinate President Charles De Gaulle.
The BBC’s Christian Fraser in Paris says Notre-Dame is the most visited landmark in France, attracting more than 13 million visitors each year, but security is relatively relaxed.
It would not be difficult to conceal a weapon in a shoulder bag, he says.
The cathedral is celebrating its 850th year.
“It’s unfortunate, it’s dramatic, it’s shocking,” the rector of Notre-Dame, Monsignor Patrick Jacquin, told the Associated Press news agency.
This was the first suicide in decades at the cathedral, he said. A few people had jumped to their deaths from Notre-Dame’s twin towers, but no-one was thought to have killed themselves at the altar before, he added.
“We will pray for this man, as for so many others at their end.”