Several Massachusetts health care providers are voicing concerns over a tentative pact that would allow Partners HealthCare, the state's largest hospital and physicians' network, to acquire at least three more hospitals. Executives from organizations including Tufts Medical Center, Beth Israel Deaconess Medical Center and Lahey Health _ all Partners competitors _ say the deal would drive up costs and lead to the closure of hospitals.

The group says in a letter that it has ``grave concerns'' about a deal struck between state Attorney General Martha Coakley and Partners, which includes Massachusetts General and Brigham and Women's hospitals.