Police arrested about 275 protesters in two U.S. cities Saturday as weekend anti-abortion demonstrations at abortion clinics continued, authorities said.

Police in Pittsburgh arrested approximately 150 members of the anti-abortion group Operation Rescue for blocking the entrance to a health clinic that performs abortions.In Milwaukee, about 125 protesters were were arrested, also for blocking the doors of an abortion clinic, police said.

The Pittsburgh protesters were arrested for blocking access to the Highland Building, which houses the Allegheny Reproductive Health Center, Operation Rescue spokeswoman Barbara Page said.