Former US president Donald Trump has said he expects to be arrested on Tuesday in a case brought by the Manhattan district attorney's office, and called on his supporters to protest.

Mr Trump said in a post on his Truth Social network on Saturday that "illegal leaks" from the district attorney's office indicated that he would be taken into custody next week.

"Illegal leaks from a corrupt & highly political Manhattan district attorney's office … indicate that, with no crime being able to be proven … the far & away leading Republican candidate & former president of the United States of America, will be arrested on Tuesday of next week," he wrote.

"Protest, take our nation back!"

He did not say what the charges would be.

A spokesperson for the district attorney's office declined to comment.

Mr Trump's lawyer, Susan Necheles, told 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.

In his postings, he repeated the false claim that the 2020 presidential election he lost to Democrat Joe Biden was stolen.

Law enforcement officials in New York have been making security preparations for the possibility that Mr Trump could be indicted.

There has been no public announcement of any time frame for the grand jury's secret work in the case, including any potential vote on whether to indict the ex-president.

Mr Trump's posting echoes one made last summer when he broke the news on Truth Social that the FBI was searching his home as part of an investigation into the possible mishandling of classified documents.

The grand jury in Manhattan has been hearing from witnesses, including former Trump lawyer Michael Cohen, who says he orchestrated payments in 2016 to two women to silence them about sexual encounters they said they had with Mr Trump a decade earlier.

Mr Trump denies the encounters occurred, says he did nothing wrong and has cast the investigation as a "witch hunt" by a Democratic prosecutor bent on sabotaging the Republican's 2024 presidential campaign.

Manhattan District Attorney Alvin Bragg's office has apparently been examining whether any state laws were broken in connection with the payments or the way Mr Trump's company compensated Mr Cohen for his work to keep the women's allegations quiet.

Mr Cohen has said that at Trump's direction, he arranged payments totalling $418,000 to porn actor Stormy Daniels, who's real name is Stephanie Clifford, and Playboy model Karen McDougal.

According to Mr Cohen, the payouts were to buy their silence about Mr Trump, who was then in the thick of his first presidential campaign.

Ms Daniels and at least two former Trump aides — one-time political adviser Kellyanne Conway and former spokesperson Hope Hicks — are among witnesses who have met with prosecutors in recent weeks.

AP/Reuters