The wife of US Treasury Secretary Steve Mnuchin has apologised for sniping at a critic on social media site Instagram who called her "deplorable" for a post highlighting her expensive clothing as she exited a government plane.
The flap erupted after Mnuchin's wife, Scottish-born actress Louise Linton, posted a photo of herself emerging from the aircraft wearing a white outfit and sunglasses, using the hashtags "#tomford," "#hermesscarf" and "#valentino".
In her initially vitriolic response to the "deplorable" criticism, Linton had lashed out about how much she and her husband contribute to the economy and pay in taxes.
On Tuesday, she scrolled back.
"I apologise for my post on social media yesterday as well as my response. It was inappropriate and highly insensitive," Linton said in a statement released through a publicist.
Linton has since made her Instagram account private.
Jenni Miller, who identified herself as a mother of three from Portland, Oregon, had said of Linton's original post on Instagram: "Glad we could pay for your little getaway. #deplorable."
Former US Secretary of State Hillary Clinton said during her unsuccessful presidential run that some of Donald Trump's supporters were a "basket of deplorables".
"Do you think the US govt paid for our honeymoon or personal travel?! Lololol," Linton shot back at Miller.
"Have you given more to the economy than me and my husband? Either as an individual earner in taxes OR in self sacrifice to your country? I'm pretty sure we paid more taxes toward our day 'trip' than you did."
The high-end fashions Linton called out in her post carry hefty price tags, with Hermes scarves retailing from $US300 ($A379) to more than $US2300 ($A2907).
Mnuchin is a former Goldman Sachs executive and Hollywood film financier.
Linton has been at the centre of controversy before.
Last year she withdrew a self-published book in which she claimed to have been caught up in violence in Zambia.
African leaders and aid workers said the book was filled with factual errors.
