The Vatican has criticised a group of nuns for challenging settled doctrines and failing to speak out against equal marriage and abortion.

The Leadership Conference of Women Religious was assessed by the Vatican and found to have “serious doctrinal problems”, the New York Times reports.

The nuns were accused of “radical feminism” and of challenging what it believes to be settled issues.

The group was formed in 1956 and has 1,500 members.

Sister Simone Campbell is a director of Network, a Catholic social justice lobby which was begun by its members and criticised by the Vatican for focusing its work on economic injustice rather than opposition to abortion and marriage equality.

She told the New York Times: “We haven’t violated any teaching, we have just been raising questions and interpreting politics.”

A statement on the group’s website said it was “stunned” by the assessment.

“Because the leadership of LCWR has the custom of meeting annually with the staff of CDF in Rome and because the conference follows canonically-approved statutes, we were taken by surprise.

“This is a moment of great import for religious life and the wider church. We ask your prayers as we meet with the LCWR National Board within the coming month to review the mandate and prepare a response.”

Archbishop J Peter Sartain of Seattle was appointed by the head of the Congregation for the Doctrine of the Faith to lead a five-year reform of the women’s group.

The archbishop has said in the past that the “unique sacrifices” made by straight couples should be rewarded by a “special” system of marriage reserved for them exclusively.

He has also lent his support to a petition in the state of Washington which would see a public ballot on whether to revoke citizens’ rights to marry a person of the same sex. He wrote of treating people with love, but said “sexual intercourse is so intimate and significant that it is intended only for a man and woman in marriage”.