Writing on social media after Russian state media reported the release, Trump said it had followed a request he "made directly" to Putin last week.

Some other releases of detained Americans from Russia have been obtained through prisoner swaps.

Trump also appeared to defend his recent decision to suspend sanctions on Russia two days before they were due to come into force, writing that "if sanctions would have been placed", negotiations for Hubbard's release "would have come to a complete and total halt".

The US state department had previously classified Hubbard, from Michigan, as "wrongfully detained" and the US president had suggested on Tuesday that his release may be imminent.

"Watch what happens," Trump told reporters, "we have been focused ⁠on ​Hubbard".

CBS News, the BBC's US media partner, reported that Hubbard had been in poor health and was expected to be flown to Texas for treatment.

Witkoff praised Putin for releasing Hubbard: "You talk so much about my president, President Trump, being a humanitarian - you are a humanitarian also sir, and I salute that. I commend you."

Hubbard was later seen thanking Witkoff as they met separately. Putin's financial adviser Kirill Dmitriev was also present.

Witkoff, who had attended talks with Ukrainian President Volodymyr Zelensky in Oslo the previous day, also asked Putin to consider a number of proposals agreed in the Norwegian capital, including renewing trilateral peace talks with Ukraine to try to end the war.

Putin has not publicly commented on whether any of the proposals would be acceptable for Moscow.

The Russian leader has so far rejected all proposals from Ukraine and its European allies to freeze the vast front line as it is and start peace talks.

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