Duke University scrapped plans on Thursday to allow the Muslim call to prayer to emanate from its chapel bell tower, university officials said, amid fierce criticism from conservative Christians and anger from alumni.

Earlier in the week, university officials said the weekly chant by Muslim students, known as the adhan, would be amplified from Duke Chapel beginning on Friday.

"Duke remains committed to fostering an inclusive, tolerant and welcoming campus for all of its students," said university spokesman Michael Schoenfeld in a statement announcing the reversal. "However, it was clear that what was conceived as an effort to unify was not having the intended effect."

The university, which has Methodist roots but is non-sectarian, reversed course after criticism from conservative Christians, most notably North Carolina-based evangelist Franklin Graham, who urged donors and alumni to boycott the university in a Facebook post.

"As Christianity is being excluded from the public square and followers of Islam are raping, butchering, and beheading Christians, Jews, and anyone who doesn't submit to their Sharia Islamic law, Duke is promoting this in the name of religious pluralism," wrote Graham, son of well-known pastor Billy Graham, in a post that received thousands of supportive comments.

The Gothic-style Duke Chapel, one of the school's best-known landmarks, is an interfaith locale where Hindu students, as well as groups from various Christian denominations, hold services.

Muslim students have held Friday services in the building's basement for several years.

On Friday, students will for the first time say the call to prayer marking the beginning of their service in an area outside of the chapel, Schoenfeld said. The plan to amplify the chant from the tower may be revisited at a later date, he said.

Schoenfeld said the school received negative feedback from the university community, including alumni, upon announcing the amplification plans.

That criticism, along with safety concerns, prompted the reversal, he said.

More than 700 of Duke's nearly 15,000 students identify as Muslim, according to the university.

(Reporting by Marti Maguire; editing by Jonathan Kaminsky and Eric Walsh)