WORCESTER — Racist and anti-Semitic stickers were recently discovered posted on campus buildings, Clark University President David Angel said in a message to the school Tuesday afternoon.

Mr. Angel did not say what the stickers specifically showed, but he said they were the work of Vanguard America, a white nationalist group. The president said he told Clark staff to take the offending materials down.

"We at Clark University refuse to be a platform for this hate speech," Mr. Angel said in Tuesday’s statement, adding that Vanguard America "has posted on other college campuses over the past year."

The university has not found out who is responsible for the postings at Clark. According to the Anti-Defamation League, Vanguard America has an active chapter in Massachusetts. Vanguard America "is best known for posting white supremacist fliers at universities across the country throughout the 2016-17 school year," the ADL says on its website.

According to Mr. Angel, staff in the school’s Student Affairs department and Office of Diversity and Inclusion were available to "offer support as needed" to anyone on campus troubled by the postings.