Penn Medicine, Mercy Health System of Southeastern Pennsylvania, and St. Mary Medical Center have formed an alliance to develop joint clinical programs in Bucks County and to explore ways to increase access to care in West Philadelphia, the nonprofit health care providers said Thursday.

"We are excited to work with these new partners to develop innovative public-health programs and initiatives that will offer patients continued access to high-quality care close to home, as well as advanced care at Penn Medicine hospitals when needed," Ralph W. Muller, chief executive of the University of Pennsylvania Health System, said in a news release.

St. Mary chief executive James Woodward said in a news release that Penn alliance would bring new surgical subspecialties in cancer care to the Langhorne institution, jointly expand ambulatory services in Bucks County, and add new programs, such as behavioral health and substance-abuse treatment.

In West Philadelphia, where Mercy Philadelphia Hospital is about two miles from the Hospital of the University of Pennsylvania, the partnership will explore ways to overcome gaps in preventive care and ensure that patients with high-risk, high-cost health conditions get the care they need.

Mercy, which includes Mercy Fitzgerald, Mercy Philadelphia, Nazareth Hospitals, and St. Mary, remains part of Trinity Health, which is based in Livonia, Mich., and is among the nation's biggest Catholic health systems. Trinity has been trying to sell its operations in New Jersey. It has a preliminary deal to sell Lourdes Health System to Virtua.