US President Donald Trump said on Wednesday he was thrilled to make his first flight aboard his new Air Force One plane, thanking Qatar for the controversial gift of the luxury jet.

Trump said the United States “couldn’t build a plane like this” — despite the fact that the heavily modified Boeing 747-8 aircraft was originally made there.

“To be honest with you, I’m excited about the first flight. Nobody’s ever seen anything like it,” Trump told journalists travelling with him, including an AFP photographer, ahead of a trip to North Dakota.

The 80-year-old president is due to attend an event at the Theodore Roosevelt Presidential Library as part of celebrations for the 250th anniversary of American independence.

“They just completed it. They made it appropriate for a president, that means the security and all of the different bells and whistles they put on. Very complex stuff, but it’s really quite something,” Trump said at Joint Base Andrews near Washington.

Critics have raised a host of ethical, constitutional and security concerns about the gifting of an aircraft worth hundreds of millions of dollars by a foreign power like Qatar.

The wealthy Gulf emirate, which is also playing a key role as a mediator in talks between the US and Iran, donated the jet last year. It has since undergone major modifications and testing.

The first flight also comes just a day after Trump faced further ethical scrutiny over filings that showed he earned around $1.2 billion dollars from his family’s cryptocurrency ventures in his first year back in power.

But Trump dismissed any suggestion of impropriety, saying the cost to US taxpayers of adapting the Qatari jet was “very little relative to what it would cost if we did it a different way”.

“Frankly, we couldn’t build a plane like this because we wouldn’t be willing to spend the kind of money necessary. They spent top dollars,” Trump told reporters.

Trump said he had asked the Emir of Qatar if he could use the plane, but “he said ‘no, no, I’d like to make a contribution to the country, so it was very nice.”

The plane will serve as a stopgap until Boeing delivers two new purpose-built Air Force Ones, which are expected to be delivered in two years after a series of delays and cost overruns.

Trump has long been obsessed with replacing the ageing current Air Force One fleet, although one of them appeared to be travelling as a backup for him on Wednesday.