First daughter Ivanka Trump and her husband Jared Kushner have apparently imposed a bizarre rule on Secret Service agents assigned to protect them – a rule that has cost US taxpayers more than $100,000 ($A128,400).

According to a report in the Washington Post, the couple have barred agents from using any of the 6.5 bathrooms in their Washington DC mansion.

“Many US Secret Service agents have stood guard in Washington’s elite Kalorama neighbourhood, home over the years to Cabinet secretaries and former presidents,” the paper reported on Thursday (US time).

“Those agents have had to worry about death threats, secure perimeters and suspicious strangers. But with the arrival of Ivanka Trump and Jared Kushner, they had a new worry: Finding a toilet.”

Perhaps even worse, one of the eventual solutions involved Michelle and Barack Obama.

Agents who needed to spend a penny while guarding President Donald Trump’s daughter and her family first set up a portaloo on the footpath outside the couple’s 460-square-metre house.

That didn’t go down at all well with the neighbours – particularly given Ms Trump and Mr Kushner’s apparent high-handed behaviour.

“They sort of came in with the attitude, like, ‘We are royalty’,” said Dianne Bruce, who lived across the street until recently.

“When they put the porta-potty right outside on the sidewalk we weren’t allowed to walk on, that was when people in the neighbourhood said, ‘That’s really not acceptable’.”

So the Secret Service came up with a new plan – and that’s where the Obamas come in. For a time, agents used a bathroom in a garage at the former first couple’s nearby house – until it all went horribly wrong.

“A Secret Service supervisor from the Trump-Kushner detail left an unpleasant mess in the Obama bathroom at some point before the fall of 2017,” reports the Washington Post.

But still Ms Trump and Mr Kushner refused to relent.

Their Secret Service detail then had to drive 1.6 kilometres to Vice-President Mike Pence’s official residence, where they had permission to use a standalone guard station. Sometimes, agents who had been caught short didn’t have time to make the drive and “relied on the hospitality of nearby restaurants”.

“It’s the first time I ever heard of a Secret Service detail having to go to these extremes to find a bathroom,” one law enforcement told the Post.

Tweet from @washingtonpost

Finally the desperate agents found a toilet to call their own. To do so, they rented a basement studio – complete with bathroom – from Kay Kendall, who lives in the area and owns another house across the street from the couple.

Ms Kendall said she wasn’t surprised when agents knocked on her door in September 2017.

“I think it was very clear that they just needed a place to take a shower, take a break, use the facilities, have lunch,” she said.

“I’m happy to be able to have helped them.”

The paper estimates the basement rental has cost $3000 ($A3800) a month since September 2017.

A White House spokesperson has disputed the newspaper’s account, saying it was the Secret Service that decided agents would not enter Ms Trump and Mr Kushner’s home.

But the Post is standing by its story. It said a law enforcement official had insisted agents were kept out “at the family’s request”.