BOSTON (AP) — The four Roman Catholic bishops of Massachusetts will urge parishioners to fight an Obama administration regulation requiring church-affiliated employers to cover birth control.

The regulation also requires employers to cover the morning-after pill, which some religious conservatives say is tantamount to abortion.

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Both contraception and abortion are opposed by the Catholic church. In letters to be read or handed out at Mass, the bishops say the ruling forces religious organizations to violate their beliefs or face large penalties.

They say it’s a blow to religious liberty, and they will not “comply with this unjust law.”

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Some Catholic groups who oppose the regulation supported Obama’s health care overhaul. But they thought religious groups would be more broadly exempted from the controversial regulation.

The administration says it won’t reconsider the decision.

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Copyright 2012 The Associated Press.