New York's attorney general is ordering Donald Trump's charitable foundation to immediately stop fundraising in the state, saying the Trump Foundation was breaking a law that requires charities to register with the state.
"The failure immediately to discontinue solicitation and to file information and reports ... with the Charities Bureau shall be deemed to be a continuing fraud upon the people of the state of New York," according to a letter dated on Friday that the attorney general's office posted online.
The "notice of violation," issued by the office of New York state Attorney General Eric Schneiderman, followed a report in The Washington Post that Trump's charity had been soliciting donations without being properly registered.
The cease-and-desist order could undercut Mr Trump's efforts to make the Clinton Foundation, the family charity of Democratic rival Hillary Clinton, a central line of attack in his presidential campaign against her.
Mr Trump has attacked the Clinton family charity as a "pay-to-play" operation under which the former secretary of state and her husband, former President Bill Clinton, rewarded big donors to the foundation with access.
The scrutiny on the Trump Foundation came as the Republican presidential candidate was dealing with a torrent of bad news, including his shaky debate performance against Ms Clinton on September 26 and the release by the New York Times of tax records that showed Trump taking an almost $US1 billion (NZ$1.3 billion) loss in 1995 that may have allowed him to avoid paying federal income taxes for up to 18 years.