President Donald Trump's administration has asked Kimberly Guilfoyle to resign from her position as US ambassador to Greece, according to White House Press Secretary Katie Zacharia.

Guilfoyle, a former Fox News host, was facing mounting scrutiny over reports she allegedly asked a Trump donor to pay her hefty credit card bill in exchange for access to the administration and behaved inappropriately while in Athens.

Trump said on Tuesday that she had done a good job, but will "not be there" in Greece any longer. "I didn't like what I read," he said.

Guilfoyle vowed to defend herself, calling the claims false, and said the ambassadorship had been the "honour of a lifetime".

Zacharia announced during her first - and unusually short - media briefing that Guilfoyle "had been asked to resign" without providing more details.

"She has been a wonderful asset to the team, and we wish her well," she said.

Guilfoyle, the 57-year-old ex-wife of California Governor Gavin Newsom, was first nominated as envoy to Athens in December 2024, a month before Trump returned to the White House as president.

Around the same time, news broke that she had broken up with Donald Trump Jr, to whom she was engaged.

In a lengthy post on X on Tuesday, Guilfoyle thanked President Trump, said she would always be a loyal supporter and denied any wrongdoing.

"I intend to vigorously defend my name, my reputation, and my integrity," she wrote, adding she will "not allow false accusations to define my decades of public service".

Her position had become increasingly tenuous as allegations of improper behaviour mounted over the past week.

A series of text messages seen by the BBC - and first reported by The Wall Street Journal - appear to show Guilfoyle asking for the money from Eric Deters, a long-time Trump ally.

"It won't show up anywhere if you wire money to American Express," she wrote in one Signal message.

In another message - dated just days before her US Senate confirmation hearing last July - Guilfoyle wrote: "Honey please I need you to get this done for me today."

Guilfoyle's lawyers disputed the authenticity of the messages and said she was asking for money owed to her for speeches and consulting work conducted on behalf of Deters before she became ambassador.

Audio recordings obtained by the Wall Street Journal reportedly include Guilfoyle bragging about her connections to prominent Greek business tycoons who she said bankrolled luxury travel and flights on private jets.

According to the newspaper, she also boasted to an official in Athens that the US could topple the Greek government.

Secretary of State Marco Rubio, who was pictured alongside Guilfoyle during a trip to Athens last week, also had reportedly become unhappy with the allegations.

Following the news that Guilfoyle was being asked to leave, Deters told the BBC that "it's a great day for American diplomacy".

Deters, who said he did not ultimately pay Guilfoyle, also said it was a "complete lie" that he owed her money for speaking and consulting fees and said he is planning to take legal action against her.

Guilfoyle was a longtime political ally of Trump's and was for years in a relationship with Trump Jr. They became engaged in 2018 and broke up in late 2024.

Trump said on Tuesday that "she, I guess, dated my son a long time ago" but was not like a family member.

The US president said he did not speak with Guilfoyle before she was asked to resign.

"She went to Greece, she was doing a good job, but we didn't like what we were reading," Trump said.

The president also said he thought Zacharia was "very good" in her first White House press briefing.

Zacharia, a longtime conservative commentator and Trump supporter, only answered a handful of questions during the 14-minute briefing.

For the first eight minutes, she read a list of what the administration saw as policy achievements. Then Zacharia answered questions about Guilfoyle, Ukraine, her family, and administration policies towards non-traditional media outlets.

She said she viewed her job as working to "amplify, multiply and expand upon President Trump's incredible agenda".