Police are looking into an anonymous letter mailed from a London address to a Manhattan mosque that allegedly threatened a massacre "on a scale never seen," authorities say.

Police were called to the Masjid Manhattan Mosque at 30 Cliff St. in the Financial District Wednesday afternoon.

A man showed a letter mailed to the mosque reading, "We will be coming to your mosque in August to carry out a massacre. It will be on a scale never seen. The one in Canada will pale in comparison. Have a nice day."

The NYPD's Hate Crimes Task Force is investigating.

Local elected officials released a joint statement Thursday, reading, "Threatening a massacre at a house of worship is fundamentally an attack on the values and core principles of our nation, our city, and our borough."

"A political climate that fosters hatred and fear continues to have very real consequences in our neighborhoods," continued the statement from state senator Daniel Squadron, congressman Jerrod Nadler, Manhattan Borough President Gale Brewer, assemblywoman Yuh-Line Niou and councilwoman Margaret Chin. "We stand united with the Muslim community and all New Yorkers in denouncing this threat, and the hateful rhetoric that creates this climate."