The timing for when Kyiv will receive the aircraft, how many will be delivered, and which countries will provide them remains unclear, but the official stressed they will not be used for an upcoming counteroffensive against Russia.

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President Joe Biden has also endorsed the training of Ukrainian pilots to fly F-16s, the White House said.

Until now, he had refused his Ukrainian counterpart Volodymyr Zelenskyy's requests for the jets.

The two leaders now set to hold face-to-face talks over the weekend, with Mr Zelenskyy confirmed to be jetting into Hiroshima, Japan, for the G7 summit.

Japan's foreign ministry announced he would arrive on Sunday to meet with Prime Minister Fumio Kishida, and America's national security chief Jake Sullivan said a Zelenskyy-Biden summit was also a "safe bet".

Western leaders have argued that training on the aircraft would take too long. It would also be some of the most sophisticated hardware provided for Ukraine, raising the stakes between Russia and the West.

It is understood the F-16s may not necessarily come from the US.

The move is part of a long-term effort to strengthen Ukraine's security, the White House official said.

"Discussions about improving the Ukrainian Air Force reflect our long-term commitment to Ukraine's self-defence," the senior Biden administration official added.

Mr Biden said in an interview with ABC News in February that US military advice showed Ukraine did not need F-16s at the time.

"I'm ruling it out for now," he said.

However, Mr Biden informed G7 leaders on Friday that the US will support efforts to train Ukrainian pilots how to fly F-16s.

The effort to train Ukrainian pilots on the jets could start in the coming weeks, the official said.

The training will "take place outside Ukraine at sites in Europe and will require months to complete", the official added.

Dutch prime minister Mark Rutte said: "Together with my British, Danish and Belgian colleagues we welcome the news that the United States stands ready to approve the training of Ukrainian pilots on F-16 fighterjets."

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Colin Kahl, the Pentagon's top policy official, previously told Congress that training Ukrainian pilots on F-16s could take "about 18 months".

Other US defence officials have said the training could be shortened to only six to nine months based on pilots' previous training and knowledge of fighter aircraft.

Mr Kahl has previously said that it could cost up to $11bn (£9bn) to revitalise Ukraine's military with F-16 jets.

G7 leaders have not announced who would pay to provide Ukraine with the planes.

In March, NBC News reported that two Ukrainian pilots were in the US undergoing an assessment to determine how long it could take to train them to fly attack aircraft, including F-16s.

Washington had also approved bringing up to 10 more Ukrainian pilots to the US for further assessment.