US President Donald Trump's administration intends to accept a Boeing 747-8 plane as a gift from the Qatari royal family that would then be outfitted to serve him as Air Force One, according to a source briefed on the matter.

The luxury plane, which would be one of the most valuable gifts ever received by the US government, would eventually be donated to Trump's presidential library after he leaves office, the source said. A new commercial 747-8 costs approximately US$400 million.

ABC News was first to report the planned gift on Sunday.

Democrats and good government advocates condemned the proposal, saying it raised massive ethical and legal concerns.

"Nothing says 'America First' like Air Force One, brought to you by Qatar," Senate Democratic leader Chuck Schumer wrote on X. "It's not just bribery, it's premium foreign influence with extra legroom."

White House press secretary Karoline Leavitt said in a statement, "Any gift given by a foreign government is always accepted in full compliance with all applicable laws. President Trump's administration is committed to full transparency."

A Qatari spokesperson, Ali Al-Ansari, told the New York Times that the possible transfer of the aircraft was still under consideration and "no decision has been made," the newspaper reported.

Trump has expressed frustration at the delays in delivering two new 747-8 aircraft to serve as an updated Air Force One. During his first term, Trump had reached a deal with Boeing to deliver the jets in 2024. A US Air Force official told Congress last week that Boeing had proposed finishing the planes by 2027.

Trump toured the Qatari-owned 747-8 in February when it was parked at Palm Beach International Airport in Florida, near Trump's Mar-a-Lago resort. At the time, the White House said the president did so to get a better understanding of how the updated Air Force One planes would be configured.

In a statement, a spokesman for Citizens for Responsibility and Ethics, a good government organisation based in Washington, questioned whether the transfer might violate the Constitution's ban on US officials accepting gifts from foreign governments absent congressional approval.

"This sure looks like a foreign country that the president has personal business dealings in giving the president a US$400 million gift right before he meets with their head of state," the spokesman, Jordan Libowitz, said.

Trump is set to visit Qatar during a trip to the Middle East this week. The aeroplane will not be presented or accepted while Trump is in Qatar.

ABC reported, citing sources, that lawyers for the White House counsel's office and the Department of Justice had prepared an analysis concluding that it would be legal and constitutional for the Defence Department to accept the plane as a gift and later transfer it to Trump's presidential library. (Reuters)