President Donald Trump has cancelled Secret Service protection, which had been arranged for Kamala Harris by Joe Biden before he left office, according to one of her advisers.

As a former vice-president, Ms Harris was entitled under law to receive six months of this extra security after leaving office in January, which was due to expire in July.

Her protection had been extended for another year by an executive directive signed by her former boss but this was revoked by Trump in a memo, seen by the BBC, which is dated Thursday.

The move comes just weeks before Harris embarks on a national book tour to promote "107 Days" - a memoir of her short-lived and ultimately unsuccessful presidential campaign in 2024.

A copy of a letter seen by the BBC, dated 28 August, directs the Secret Service to "discontinue any security-related procedures previously authorised by Executive Memorandum, beyond those required by law" for Harris from 1 September.

A senior White House official confirmed the move.

Sources familiar with the situation told CBS, the BBC's US news partner, that a recent threat assessment found nothing alarming that would warrant extending her detail past the legally-mandated six month period she was entitled to.

In 2008, the US Congress enacted a law permitting the Secret Service to provide protection to former Vice Presidents, their spouses and any children under the age of 16 after leaving office.

It has been just over seven months since Harris left office at the end ofJoe Biden's administration in January.

Harris' husband, Doug Emhoff, had his own protections end on 1 July at the end of the legally mandated period provided to the spouses of former vice-presidents.

The loss of Harris' secret security protection means she will lose the agents that are assigned to protect her and her property in Los Angeles, as well as proactive threat intelligence carried out to identify and pre-empt any potential threats.

The price of similarly protections, if privately funded, could add up to millions of dollars per year.

California Governor Gavin Newsom and Los Angeles Mayor Karen Bass have both expressed outrage at the announcement.

"This is another act of revenge following a lost list of political retaliation in the form of firings, the revoking of security clearances and more," Ms Bass told CNN, who were first to report the story.

The LA mayor said this puts Harris in danger and she would make sure she was safe in Los Angeles.

Since returning to the White House in January, Trump has revoked Secret Service protections for a number of people, including Hunter and Ashley Biden, the children of the former president, and Anthony Fauci, the former director of the National Institute of Allergy and Infectious Diseases.

Several former Trump officials and allies have also had their protections revoked, including ex-Secretary of State Mike Pompeo and John Bolton, a former national security adviser who had become a vocal critic.

Harris faced several security threats during her time in office, and former Secret Service officials have said that the dangers were compounded by the fact that she was the first woman and first person of colour to serve in the office.

In August 2024, for example, a Virginia man was charged with making online threats to kill, kidnap or injure Harris and former President Barack Obama.

In an earlier incident in 2021, a 39-year-old Florida woman pleaded guilty to making threats against Harris after admitting she sent videos to her imprisoned husband in which she displayed weapons and said that a "hit" could be carried out within 50 days.