The FBI is investigating the source of offensive graffiti at the Islamic School of Rhode Island in West Warwick.

The agency's Boston division announced Monday it has begun a civil rights investigation into the vandalism Saturday night.

School officials say the entrance was tagged with orange graffiti that read "Now this is a hate crime," "pigs" and offensive references to Muhammad.

Hilmy Bakri, president of the school's board of trustees, said the school has never before been the subject of vandalism or any serious threats. It opened in 2004.

A news conference has been scheduled for 11 a.m. Tuesday in the gym with community leaders from other faiths and government officials to show solidarity.