- One of Mr Trump's lawyers said his claim was based on media reports that he could be indicted next week.
- If Mr Trump is indicted, it would be the first criminal case ever brought against a former US president.
Former US President Donald Trump says he is expecting to be arrested on Tuesday in a case about alleged hush money paid to an ex-porn star.
Mr Trump called on his supporters to protest against such a move in a post on his Truth Social platform.
One of Mr Trump's lawyers said his claim was based on media reports that he could be indicted next week.
If Mr Trump is indicted, it would be the first criminal case ever brought against a former US president.
It would also have serious ramifications for his campaign to become the Republican nominee in the 2024 presidential election.
For five years, prosecutors in New York have been investigating allegations that hush money was paid on Mr Trump's behalf to former porn star Stormy Daniels prior to the 2016 presidential election.
Ms Daniels says she was paid $130,000 (£107,000) by Mr Trump's former lawyer Michael Cohen before the 2016 election in exchange for silence about an alleged affair. Mr Trump denies they had sexual relations and has dismissed the case as being politically motivated.
It is one of several cases in which the 76-year-old is currently being investigated, although he has not yet been charged in any and denies wrongdoing in each.
On Saturday Mr Trump wrote on his social networking site Truth Social that "illegal leaks" from the Manhattan district attorney's office "indicate" he would be arrested on Tuesday.
The district attorney's office has not yet commented. Mr Trump's lawyer, Susan Necheles, told the BBC's US partner CBS News that his post was "based on media reports".
"Since this is a political prosecution, the district attorney's office has engaged in a practice of leaking everything to the press, rather than communicating with President Trump's attorneys as would be done in a normal case," she said.
The Republican Speaker of the US House of Representatives, Kevin McCarthy, hit out at the investigation, calling it "an outrageous abuse of power by a radical DA [district attorney]".
In a tweet, he also promised to investigate whether federal money was being used to interfere in elections "with politically motivated prosecutions".
US media organisations say law enforcement agencies in New York are preparing for the possibility of Mr Trump being indicted and appearing in a Manhattan courtroom as early as next week.
There were signs the Stormy Daniels case was progressing when earlier this month, Mr Trump was invited to testify to a grand jury - which determines whether there is enough evidence to pursue charges in a case.
The hearings are held in secret and several former aides of Mr Trump have reportedly testified in this case.
Experts suggest the offer to testify indicates he could soon face criminal charges - but it is not clear what these could be.
According to the Associated Press, law enforcement officials are considering the practicalities of taking a former president into court, including questions around security.
Another lawyer for Mr Trump, Joseph Tacopina, told the news agency "we will follow the normal procedures" if he is indicted.
In addition to the Stormy Daniels case, Donald Trump faces a separate criminal investigation over efforts to overturn his narrow loss in the state of Georgia in the 2020 presidential election - though it is not known if the former president is being directly investigated.
The Department of Justice is also looking at whether classified government documents were handled incorrectly after Mr Trump left office, as well as broader efforts to undermine the results of the election three years ago - including the 6 January attack on the US Capitol.