DILLEY, Texas — About 80 faith leaders from around the U.S. have signed a letter to President Obama urging the government to stop detaining immigrant families, while high-ranking clerics visiting a South Texas detention facility Friday criticized the practice.

The U.S. government opened the detention centers, including two in Texas, in response to the tens of thousands of immigrants who crossed the U.S.-Mexico border last summer. Most were women with children or unaccompanied minors from Central America.

In their letter, released Friday, Christian and Jewish clerics decried the policy of detaining mothers and children as “inappropriate and unjust.” Detention is harmful to children, they said, and leaves the mothers with diminished access to the legal system.

Archbishop Gustavo Garcia-Siller of San Antonio, along with four other Catholic and Lutheran bishops, toured the South Texas Family Residential Center in Dilley Friday, speaking with some of the 390 women and children housed there. The facility is expected to eventually hold 2,400 people.

U.S. Customs and Immigration Enforcement said in a statement that the centers are an important response to the surge in illegal immigration last summer and an effective and humane way to keep families together. ICE said its centers “operate in an open environment, which includes medical care, play rooms, social workers, educational services, and facilitate access to legal counsel.”