The LCWR, a Maryland-based umbrella group that claims about 1,500 leaders of U.S. women's communities as members, represents about 80 per cent of the country's 57,000 women religious.

The announcement from the Vatican's Congregation for the Doctrine of the Faith came in an eight-page "doctrinal assessment," based on an investigation that Blair began on behalf of the Vatican in April 2008. That investigation led the doctrinal congregation to conclude, in January 2011, that "the current doctrinal and pastoral situation of LCWR is grave and a matter of serious concern, also given the influence the LCWR exercises on religious congregation in other parts of the world."

Among the areas of concern were some of the most controversial issues of medical and sexual ethics in America today.

"While there has been a great deal of work on the part of LCWR promoting issues of social justice in harmony with the Church's social doctrine, it is silent on the right to life from conception to natural death, a question that is part of the lively public debate about abortion and euthanasia in the United States," the doctrinal congregation said. "Further, issues of crucial importance in the life of the Church and society, such as the Church's biblical view of family life and human sexuality, are not part of the LCWR agenda in a way that promotes Church teaching."

The Vatican also found that "public statements by the LCWR that disagree with or challenge positions taken by the bishops, who are the Church's authentic teachers of faith and morals, are not compatible with its purpose."

According to the Vatican, such deviations from Catholic teaching have provoked a crisis "characterized by a diminution of the fundamental Christological centre and focus of religious consecration."

But the congregation's document also praised the "great contributions of women religious to the Church in the United States as seen particularly in the many schools, hospitals and institutions of support for the poor, which have been founded and staffed by religious over the years," and insisted that the Vatican "does not intend to offer judgment on the faith and life of women religious" in the LCWR's member congregations.

During his tenure as the Holy See's delegate, which is to last "up to five years, as deemed necessary," Sartain's tasks will include overseeing revision of the LCWR's statutes, review of its liturgical practices and the creation of formation programs for the conference's member congregations. The archbishop will also investigate the LCWR's links to two outside groups: Network, a Catholic social justice lobby; and the Resource Centre for Religious Institutes, which offers legal and financial expertise to religious orders.

The doctrinal assessment grew out of the Vatican's "Apostolic Visitation of Religious Communities of Women in the United States," a study of the "quality of life" in some 400 congregations, which began in December 2008. The visitation's final report was submitted in December 2011 but has not yet been published.