Swastikas desecrate gravestones at the First World War cemetery in Loos-en-Gohelle, northern France. (Thibault Vandermersch/Associated Press)

The graves of 12 British soldiers killed in France during the First World War were defaced with Nazi graffiti early Friday, the local government said.

Vandals painted pink swastikas and other Nazi symbols on the gravestones in the cemetery at Loos-en-Gohelle in the Pas-de-Calais.

France's minister for veterans, Hubert Falco, called the desecration "an insult to the memory" of the soldiers and an "insult to France."

Workers were cleaning up the graffiti Friday, and an investigation had begun.

A spokesman for the Royal British Legion said: "It's self-evident that these graves must be respected and any acts of desecration are held in dismay by all right-thinking people," the BBC reported.

The cemetery holds the graves of nearly 2,400 soldiers, mostly British but also Canadian, French and German, according to the Commonwealth War Graves Commission, which commemorates the 1,700,000 Commonwealth dead in two world wars in 2,500 war cemeteries and plots.

The commission website said the Canadian Corps began the Loos-en-Gohelle cemetery in 1917. But most of the graves were soldiers killed in the Battle of Loos, Sept. 25-Oct. 8, 1915, who were originally buried in smaller plots or battlefields where they fell, and then moved to Loos-en-Gohelle after the war ended.

With files from The Associated Press