Britain's King Charles to visit France on September 20-22

"This visit is an honour for France, at a time when our country will also host the Rugby World Cup," the Elysee statement said.

Britain's King Charles will travel to France on September 20-22 after a planned state visit in March was cancelled because of tense protests over reforms to the French pension system, the Elysee said on Thursday.

Royal Family: King Charles III reacts as he meets members of the public during a visit of the Sandringham Flower Show. (AFP)

"This visit is an honour for France, at a time when our country will also host the Rugby World Cup," the Elysee statement said.

"It will bear witness to the depth of the historical ties that unite our two countries and our two peoples, and will contribute to honouring French excellence and know-how."

Charles had planned a three-day visit to France in late March in what would have been his first state visit since succeeding his late mother, Queen Elizabeth, as British monarch.

But the visit was cancelled after social unrest over President Emmanuel Macron's new pension law erupted into some of the worst street violence seen in years across the country.

Instead, Charles visited Germany on his first overseas trip as king.