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Health and Human Services Secretary Kathleen Sebelius was interrupted by anti-abortion protesters Friday during her commencement speech at Georgetown University, where religious opposition to her appearance had been building for weeks.

The Catholic Archdiocese of Washington said her public actions represent a direct challenge to religious liberty. Bishops specifically object to parts of President Obama's health care law, which requires employers, including religious hospitals and universities, to offer birth control coverage in their employee health insurance plans.

Earlier this year, after an outcry from conservative lawmakers and Catholic leaders, the Obama administration said it still would require birth control coverage but would mandate that insurance providers pick up the cost instead of religious-affiliated employers who who have moral objections to birth control. Churches already are exempt from the mandate.

Georgetown, in response to calls to withdraw Sebelius’ invitation, said that the school invites a wide variety of “high-profile” speakers and that Sebelius was chosen by students in the school’s Public Policy Institute to talk at their diploma ceremony.

At least three men could be seen and heard Friday protesting her speech to graduates at the Washington school’s Public Policy Institute. The protesters were escorted out the building by police but were not arrested.

The men told Fox News afterward they are not affiliated with a political party.

Invoking President Kennedy, Sebelius called the separation of church and state "a fundamental principle in our unique democracy." She urged graduates to weigh different views in policy debates and follow their own moral compasses.

Amid applause, she also told the public-policy graduates that their “jobs will never be easy.”

The Associated Press contributed to this report.