A civil rights group on Wednesday called for additional police protection for a Providence, Rhode Island, mosque after it said it received a threatening letter calling Muslims a "vile and filthy people."
The Masjid Al-Kareem mosque was the latest in a string of mosques from California to Florida to receive the letter, according to the Council on American-Islamic Relations.
The letter referenced President-elect Donald Trump, saying that the New York businessman is "going to cleanse America and make it shine again. And, he's going to start with you Muslims."
The letter also said Trump will "do to you Muslims what Hitler did to the Jews."
During his campaign for the White House, Trump proposed a temporary ban on Muslims entering the country as a means of countering terrorism. He never retracted this statement, but in the later stages of the campaign, rephrased it as a proposal to temporarily suspend immigration from regions deemed as exporting terrorism and where safe vetting cannot be ensured.
The local chapter of the Council on American-Islamic Relations asked for additional police protection for the mosque following the threat.
"This act of hate campaign targeting a New England house of worship must be investigated by state and federal law enforcement authorities," said John Robbins, the head of the group's Massachusetts-based New England chapter.
Officials at the Rhode Island State Fusion Center, where federal, state and local law enforcement coordinate their response to threats, were not immediately available to comment on the group's request.
The Federal Bureau of Investigation earlier this month released data showing a 66 percent increase in the number of hate crimes against Muslims it investigated in 2015. That was a rise far higher than the overall 7 percent increase in hate crimes against all classes of victims.
Some of the reported hate crimes have followed attacks by assailants inspired by militant groups such as Islamic State.
In the most recent such attack, a Somali immigrant who the FBI said may have been inspired an al Qaeda-linked cleric injured 11 people in an attack at Ohio State University.