VATICAN CITY -- Pope Benedict XVI on Friday (May 18) expressed his "deep gratitude" to American nuns for their "fidelity and self-sacrifice," and he praised the U.S. bishops for their efforts to welcome immigrants.

The pontiff's comments on the sisters come just a month after the Vatican crackdown on the Leadership Conference of Women Religious, an umbrella group that represents most American nuns. The group was accused of not speaking out strongly enough against gay marriage, abortion and women's ordination.

Addressing a group of bishops from the United States who were in Rome for a regularly scheduled visit, Benedict said he hoped that the current phase of "discernment" would bear "abundant spiritual fruit" and revitalize women religious communities "in fidelity to Christ and the Church."

The pope called on the nuns to rediscover the "sublime dignity and beauty of the consecrated life" and stressed the need to strengthen communication between women religious and local church authorities.

In his speech to the bishops, Benedict also praised the church's "great generosity" towards immigrants in the United States.

He said the bishops' commitment to immigration reform was a "particular sign" of their efforts on behalf of immigrants, but conceded that it was a "difficult and complex issue" from the social, political and economical, as well as the human, point of view.

Concluding his address, Benedict seemed to echo the bishops' alarm over President Obama's policies, including the fight over the contraception mandate, saying that the American church faced the "threat of a season in which our fidelity to the Gospel may cost us dearly."