WASHINGTON (AFP) - A new book on former US president Donald Trump's time in office claims that a White House toilet would jam after attempts to flush away office papers, Axios reported on Thursday (Feb 10).

The upcoming book, Confidence Man, by New York Times journalist Maggie Haberman, says that "staff in the White House residence periodically discovered wads of printed paper clogging a toilet - and believed the president had flushed pieces of paper," according to an exclusive preview by Axios.

Trump is already being investigated for carting off 15 boxes of White House documents to his Florida residence. The National Archives, which has jurisdiction over preserving presidential papers, says that Trump also had a habit of ripping up documents - some of which have since been taped back together.

The book, based in part on Haberman's post-presidential interviews with Trump, reports that the Republican has told people he remains in touch with North Korean dictator Kim Jong Un. Letters sent by Kim to Trump during his presidency - "love letters," as Trump described them at the time - were among the documents taken to his Florida residency.

Trump issued a statement denying that he broke laws on archiving presidential documents and said he had complied "without conflict and on a very friendly basis."

"Also, another fake story, that I flushed papers and documents down a White House toilet, is categorically untrue and simply made up by a reporter in order to get publicity for a mostly fictitious book," he wrote.

Haberman's book is set to be published on Oct 4.

The veteran Times journalist has been on the Trump beat for a decade and long had unrivalled access among journalists to the property tycoon-turned-politician's inner circle.