France, April 27 -- A hand-written letter from Napoleon denying his role in the kidnapping of Pope Pius VII in 1809 is to go under the hammer this weekend, in a reminder of France's complicated past relationship with the Vatican.

The letter, signed "Napole", will go on sale at auction on Sunday, the day after the funeral of Pope Francis who died this week.

Pope Pius VII was kidnapped by French forces in his private apartments in the Quirinal Palace in Rome and remained a prisoner of Napoleon for five years.

The head of the Catholic church had sought to maintain the Vatican's sway over the French church and resisted Napoleon's desire to exert control over the clergy.

In the letter addressed to French nobleman and ally Jean-Jacques-Regi...