A row has broken out between the Vatican and the Knights of Malta, an ancient Catholic order, after a top official was sacked over a contraception scandal.
It followed revelations that the Knights' charity branch had distributed thousands of condoms in Myanmar.
The order's grand chancellor, Albrecht von Boeselager, was suspended over the matter on 8 December.
The Catholic Church forbids the use of artificial contraception.
Mr Boeselager has said he did not know about the condom distribution programme, which was an anti-HIV and family planning initiative, and stopped it when he learned of its existence.
Now the 900-year-old order is refusing to co-operate with a Vatican investigation into his sacking, and warning members that if they speak with Pope Francis's team, they must not contradict the decision by the order to replace Mr Boeselager.
In a statement on Tuesday, the Knights called the Pope's review a legally "irrelevant" move aimed at limiting the order's sovereignty.
Pope Francis appointed a five-member commission to investigate the sacking in December, amid evidence that his own envoy to the group, conservative Cardinal Raymond Burke, helped engineer it without his blessing.
In some ways, the condom dispute reflects the broader ideological divisions in the Roman Catholic Church that have intensified during Francis's papacy.
The pontiff is prone to emphasising the church's merciful side over its more doctrinaire traditions, and this stance has sometimes grieved more hardline Catholics.
The row also highlights internal divisions within the order, which dates back to the Crusades - and whether its members are fulfilling their vows of obedience.
What is the Order of Malta?
The Sovereign Order of Malta traces its history to the 11th Century, with the establishment of an infirmary in Jerusalem that cared for pilgrims of all faiths.
The lay religious order of the Catholic Church now has 13,500 members and 100,000 staff and volunteers, who provide healthcare in hospitals and clinics around the world.
The Order of Malta enjoys many of the privileges of a nation state. It issues its own stamps, passports and licence plates - and holds diplomatic relations with 106 states, the Holy See included.
The BBC's David Willey gave his impressions of the Knights' headquarters during the order's 900th anniversary:
"Today the Knights are a unique sovereign entity in that they rule over no territory except a palace in one of Rome's smartest shopping districts, a church and an elegant villa overlooking the city.
"The order's international headquarters is in a palace situated in Rome's Via Condotti, a short distance from the Spanish Steps. High fashion boutiques nearby offer neat handbags for sale at prices ranging up to $3,000.
"The atmosphere inside reminded me of an Oxbridge College or a London Club. Inside the porter's lodge there are cubby holes for letters addressed to His Highness, the Grand Master - who is British - and to senior officials."
Though the order sounds like a masculine institution, the Knights are not exclusively male. As of 2013, women made up about 30% of its members - known as the Dames.
The group is reportedly keen to shed its aristocratic image, and to attract new talent to continue its humanitarian work.