Donald Trump's Treasury Secretary Steve Mnuchin has defended requesting a Government plane for his honeymoon, saying it was a "national security issue".

The former Goldman Sachs banker reportedly requested the use of a US Air force jet during his honeymoon to France, Italy and Scotland.

Use of the aeroplane costs the US taxpayer as much as $25,000 (£18,400) an hour, according to ABC, which first reported on the matter.

Revelations about the request prompted a backlash, with the director of Citizens for Responsibility and Ethics in Washington saying Mr Mnuchin cannot "be expecting taxpayers to foot the bill for a Hollywood lifestyle".

But Mr Mnuchin said the issue was "misreported".

"This had nothing to do with convenience, this was purely about national security," he told Politico.

The Treasury Secretary said: "I probably spend around 50 per cent of my time on national security issues.

"We are dealing with, as you know, some of the most complicated issues right now, whether it be North Korea, Iran, Venezuala or anywhere else.

"So let me just set the record straight, first of all, the government has never paid for any of my personal travel.

"At the time, my staff wanted to make sure that I constantly had access to secure communications and secure information. This [using the military jet] was one of the things we explored."

Mr Mnuchin said his staff withdrew the request after finding another way to ensure he could communicate securely.

"I'm very sensitive to the use of Government funds," he added.

Government planes are typically reserved for Cabinet members and those with direct involvement in matter of national security, according to ABC. Treasury secretaries are not usually afforded the privilege, due to the high cost of flying the jets.

Mr Mnuchin's travel was already under review after accusations he used a Government-owned plane to travel to Kentucky in August to view the solar eclipse. The secretary's office said he was there for meetings about tax reform.

Mr Mnuchin, who has amassed a personal fortune of hundreds of millions of dollars, married Scottish actress Louise Linton in June. Ms Linton prompted criticism in early September after she posted a photo to Instagram of her embarking from a government jet on the same Kentucky trip. She tagged luxury designers including Valentino, Hermes, Roland Mouret, and Tom Ford.

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When a commentator criticised her for using taxpayers' money for the getaway, Ms Linton responded telling the woman to "chill out."

"Have you given more to the economy than me and my husband?" Ms Linton asked. "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. Pretty sure the amount we sacrifice per year is a lot more than you'd be willing to sacrifice if the choice was yours."

The actress later apologised, saying her remarks were "inappropriate and highly insensitive".