New York state's top prosecutor has ordered the charitable foundation run by Donald Trump to cease fundraising, saying it was operating without proper certification.

A September 30 letter from the office of Attorney General Eric Schneiderman made public on Monday informed the Trump Foundation that it "must immediately cease soliciting contributions or engaging in fundraising" in the state.

"Failure to immediately discontinue solicitation... shall be deemed to be a continuing fraud upon the people of the state of New York," the letter warned.