Catholic bishops have rejected the Obama administration's latest proposal on mandatory contraceptive coverage, vowing to continue to fight for changes before the policy becomes final.

After reviewing the administration's proposal unveiled last week, the U.S. Conference of Catholic Bishops said it stands by its earlier concerns.

"Because the stakes are so high, we will not cease from our effort to assure that healthcare for all does not mean freedom for few," New York Cardinal Timothy Dolan, president of the bishops' conference, said in a statement.

Under the federal health care overhaul, the administration has pressed to require most employers to provide access to free contraceptive coverage.

The rule exempts houses of worship and creates an "accommodation" for religious-affiliated employers like schools and hospitals -- at which employees could obtain contraceptive coverage through a separate policy.

The U.S. Conference of Catholic Bishops, though, said a bigger buffer is needed between religious charities and any third party arranging contraceptive coverage. Bishops also want a clearer statement that faith-affiliated hospitals and other nonprofits are religious ministries. And church leaders continue pressing for an exemption for owners of for-profit business who say the requirement forces them to violate their religious beliefs.

The government has given no indication that it is considering a religious opt-out for business owners.

The bishops made their comments nearly a week after the Department of Health and Human Services announced another revision on coverage for contraception. The regulation is part of President Obama's health care overhaul, known as the Affordable Care Act.

The department had no reaction Thursday to the bishops' criticism, pointing only to an earlier pledge that the government wants to find a solution that would provide the coverage to women while respecting religious concerns.

The HHS announced the proposed rules a year ago. The initial plan contained a religious exemption that many faith groups, including many who have been supportive of health care reform, said was too narrow. The rule covered churches and other houses of worship but not faith-affiliated hospitals, charities, colleges and other nonprofits.

Dozens of religious groups and for-profit business owners have sued over the regulation, saying it violates their religious rights. Advocates for the broadest coverage argued employers are trying to impose their religious beliefs on workers. The issue is expected to reach the Supreme Court.

The Obama administration, meanwhile, has been trying to develop a plan that could resolve religious concerns.

Under the proposal the government offered last week, the definition of a religious organization was simplified. It would now include, for example, a mosque whose food pantry serves the entire community and not just its own members.

For other religious employers, the new approach attempted to put a barrier between religious charities and contraception coverage. Female employees would still have free access through insurers or a third party, but the employer would not have to arrange for the coverage or pay for it. Insurers would be reimbursed for any costs by a credit against fees owed the government.

Dolan said the proposal creates an unacceptable second-class status for faith-affiliated hospitals, colleges and charities "rather than accepting the fact that these ministries are integral to our church and worthy of the same exemption as our Catholic churches." The plan for an insurer or third party to arrange birth control coverage leaves "the possibility that ministries may yet be forced to fund and facilitate such morally illicit activities," Dolan said.

"Throughout the past year, we have been assured by the administration that we will not have to refer, pay for, or negotiate for the mandated coverage," Dolan said in a statement. "We remain eager for the administration to fulfill that pledge and to find acceptable solutions."

The revised mandate is subject to a 60-day public comment period. The overall mandate is to take effect for religious nonprofits in August.

The Catholic Health Association, the hospital trade group whose support was critical for passage of Obama's health care legislation, had also sought a broader religious exemption. The association hasn't yet commented on the new proposal, but said Thursday it will do so after seeking input from members.

The Associated Press contributed to this report.