Washington: US President Donald Trump on Monday dismissed ethics concerns over his plans to receive a new Air Force One plane as a gift from Qatar.

Trump says the leadership of Qatar knew that Boeing has encountered delays building the next generation of the Air Force One aircraft and wanted to help by giving a plane to the U.S. government.

He said, “I could be a stupid person and say we don’t want a free plane” but that the gift from Qatar “helps us out” because the models he currently flies on are decades old.

“I think what happens with the plane is that we're very disappointed that it's taking Boeing so long to build a new Air Force One...This was just a gesture of good faith,” Trump said.

News of the $400 million gift prompted criticism from some Democrats and Trump allies.

Trump said the plane would ultimately be decommissioned and go to his future presidential library. He said he would not fly on it after he leaves office.

Trump said Sunday he was ready to accept a luxury Boeing 747-8 jumbo jet as a gift from the ruling family of Qatar, prompting criticism from some Democrats and allies of the president.

Press Secretary Karoline Leavitt confirmed that the Qatari royal family would donate a Boeing 747-8 jumbo jet described as a "flying palace", as Trump prepares to fly out on a Middle East tour that includes Qatar.

"The Qatari government has graciously offered to donate a plane to the Department of Defense. The legal details of that are still being worked out," Leavitt told Fox News.

"But of course, any donation to this government is always done in full compliance with the law, and we commit ourselves to the utmost transparency, and we will continue to do that."

Both the monetary size of the gift and the proposed use of a foreign-built plane as the ultra-sensitive Air Force One would be unprecedented and raise numerous ethical and security questions.

Asked if there were concerns that Qatar would want something in return, Leavitt replied: "Absolutely not, because they know President Trump and they know he only works with the interests of the American public in mind."

The US Constitution prohibits government officials from accepting gifts "from any King, Prince or foreign State," in a section known as the emoluments clause.

But there could be possible loopholes for the jet, including if it is given to the Pentagon, or if Trump later donates it to his planned presidential library after he leaves office.