Seeking to end detention of immigrant families in Pennsylvania, an alliance of Philadelphia City Council members, immigration activists, and law students unveiled a new tactic Wednesday - international pressure.

The group announced the filing of an "urgent action appeal" with the U.N. Working Group on Arbitrary Detention, a five-member panel of experts that investigates alleged human-rights abuses and makes nonbinding recommendations.

"The Berks detention center is a nightmare, worthy of international investigation," Councilwoman Helen Gym said at a City Hall news conference. She cited health and safety concerns including outbreaks of shigella, a gastrointestinal disease, and the institutional rape of a 19-year-old woman by a guard.

The appeal, supported by about 60 local, national, and international organizations, asks the United Nations to issue an opinion that family detention violates the best interests of children; is unnecessary, given alternatives to detention; and interferes with the right of refugees to seek asylum.

If the working group issues an opinion, the U.S. government will have to respond in writing, said Sarah Paoletti, director of the University of Pennsylvania Law School's transnational legal clinic.

The Berks County Residential Center, a 96-bed facility in Leesport, is run by Berks County under a contract with U.S. Immigration and Customs Enforcement. It is where immigrant mothers and their children are incarcerated pending resolution of actions to deport them. Two similar but much larger facilities are in Texas.

Last fall, the Pennsylvania Department of Human Services ruled that BCRC was out of compliance with its license to provide "residential and day treatment for court-adjudicated youth" because its population consists solely of refugee families.

Pennsylvania did not renew BCRC's license when it expired in February, but the center has been allowed to operate while it appeals the nonrenewal. The next hearing on the appeal is scheduled for Nov. 7.

Advocates say the matter has been unresolved for too long and have urged Gov. Wolf to issue an emergency removal order, shuttering Berks and relocating its population.

Wolf spokesman Jeffrey Sheridan said in a statement that "the Wolf administration has repeatedly urged the U.S. Department of Homeland Security and Health and Human Services to consider community-based options to serve these families whenever possible. Child mental health experts, court rulings, and previous federal policy all support the principle that these children should be served in a nonsecure setting."

John Farrell, a Temple University law student with the Sheller Center for Social Justice, helped draft the U.N. appeal.

He said family detention "arbitrarily deprives families of liberty, on no legal basis, by measures that are neither necessary or proportional to protect American interests."

"International human rights standards are clear that deterring future migration is not a legal means to detain current migrants," he said, even though that is the Department of Homeland Security's rationale for family detention.

"We are calling on the federal government to immediately stop payments to this detention center. We are asking them to use those resources to appropriately relocate ... these families," said Councilwoman Maria D. Quiñones-Sánchez.