Donald Trump
US President-elect Donald Trump's name was mentioned in anonymous hate mailREUTERS/Lucas Jackson

A number of mosques across the US have been told that President-elect Donald Trump 'will do to Muslims what Hitler did to Jews' in hate mail posted from an address in California.

Mosques in California, Ohio, Michigan, Rhode Island, Indiana, Colorado and Georgia have reported receiving identical letters in what the authorities have dubbed hate incidents, the Associated Press reports.

The racist mail refers to Muslims as "vile and filthy people" in correspondence that is being investigated by the police, with the FBI not yet involved but monitoring the situation.

The president of the Islamic Centre of Cleveland, Shehadeh Abdelkarim, whose mosque got sent one of the letters addressed to "the children of Satan", said the return address featured the name Reza Khan, which authorities confirmed was a 'bogus' name. "The person obviously knows a little about Muslim culture," Abdelkarim told AP.

The identical letters, which are reportedly photocopies of a handwritten letter, often feature the same return address but use a postcode which is from an area many miles away.

The Council on American-Islamic Relations has called on the FBI to get involved in the investigation, with the Massachusetts chapter of the Council (CAIR-MA) requesting stepped-up police protection of local mosques after it received one of the Islamophobic letters.

It is not the first anti-Muslim incident which has been reported following Trump's victory in the 8 November presidential election, in an increase in hate crime that many see as fuelled by Trump's campaign rhetoric about banning Muslims from entering the country.

Trump eventually backtracked on his suggestion of a temporary Muslim ban at US ports of entry, instead suggesting 'extreme vetting', although it is unclear how this would be carried out.