The ousted Grand Master of the Knights of Malta Catholic charity will attend a meeting that could elect his successor, the group said on Wednesday, in a direct defiance of Pope Francis' order for him to stay away.
A spokesperson for the Knights said Matthew Festing, who resigned on Jan. 24, had informed the group that he would come to the meeting this Saturday at its headquarters in Rome.
It was not clear if he would stand for re-election, as some of his supporters have urged him to.
On April 15, Archbishop Angelo Becciu, the Vatican's deputy secretary of state, who the pope named "special delegate" to the ancient chivalric group, ordered Festing not to travel to Rome for the election.
"Your presence would re-open wounds, only recently healed, and would prevent the event taking place in an atmosphere of peace and regained harmony," Becciu said in a letter, a copy of which was obtained by Reuters from a Vatican source.
Becciu said in the letter the pope "shared" his decision and asked Festing to stay away as "an act of obedience".
Festing tendered his resignation to the pope after a month-long, highly public spat with the Vatican over the group's sovereignty.
The turmoil began in December when Festing, a Briton, fired Albrecht Freiherr von Boeselager, the German-born Grand Chancellor of the aristocratic order.
Festing and conservative U.S. Cardinal Raymond Leo Burke, the group's chaplain and a frequent critic of the pope, had accused Boeselager of violating Church rules by turning a blind eye to the use of condoms in aid projects in the developing world when he was in a previous post.
Festing, who defiantly ordered members not to cooperate with a papal investigation of events surrounding Boeselager's dismissal, lost his battle with the Vatican and became the first Grand Master in centuries to resign instead of ruling for life.
The Vatican concluded the condom issue was just an excuse by Festing and Burke to wield more power in the 970-year-old organisation and Boselager was reinstated.
The Knights of Malta counts some 13,000 members, 80,000 volunteers and about 25,000 paid employees, mostly medical staff who run charities and development projects around the world.
The all-male top leaders are not clerics but take vows of poverty, chastity and obedience to the pope.
The Vatican wants this weekend's vote to elect an interim leader to run the group for a year while its constitution is changed. But the group could also decide to elect a new Grand Master.