The head of the Knights of Malta, who has been locked in a bitter dispute with the Vatican, has resigned, a spokesperson for the Rome-based Catholic chivalric and charity institution said on Wednesday.

The spokesperson said Grand Master Matthew Festing had resigned after Pope Francis asked him to step down at a meeting on Tuesday. Grand Masters of the institution, which was founded in the 11th century, usually keep their positions for life.

"The Pope asked him to resign and he agreed," the spokesperson said, adding that the next step was a formality in which the group's Sovereign Council would have to sign off on the highly unusual resignation. The order would be run by its number two, or Grand Commander, until a new head is elected.