WASHINGTON • The July 7 meeting in Hamburg, Germany, was the single most scrutinised of the Trump presidency. But it turned out there was another, potentially just as important, encounter - a roughly hour-long, one-on-one discussion over dinner that was overheard only by a Kremlin-provided interpreter.

No presidential relationship has been more dissected than the one between US President Donald Trump and his Russian counterpart Vladmir Putin, a dynamic heightened only by the swirl of investigations into whether Mr Trump's campaign colluded with Russia to sway the election in his favour.

News of the meeting came as Mr Trump nominated former Utah governor and one-time Republican presidential candidate Jon Huntsman Jr as his envoy to Moscow, the White House said on Tuesday.

Mr Huntsman, 56, was ambassador to Singapore under former president George H.W. Bush and ambassador to China under former president Barack Obama.

The meeting was confirmed by the White House only on Tuesday, after some attendees privately expressed surprise that it had occurred. The dinner discussion caught the attention of other leaders around the table, some of whom later remarked privately on the odd spectacle of an American president seeming to single out the Russian leader for special attention at a summit that included some of the US' staunchest, oldest allies.

The White House acknowledged the conversation on Tuesday but said there was nothing unusual about it, batting aside the suggestion that it had been deliberately hidden from public view.

Late on Tuesday night, Mr Trump derided news reports about it as "sick". He said the dinner was not a secret, since all of the world leaders at the summit meeting and their spouses were invited by Chancellor Angela Merkel of Germany. "Press knew!" he tweeted. "Even a dinner arranged for top 20 leaders in Germany is made to look sinister!"

While the private leaders-and- spouses dinner was on Mr Trump's public schedule, the media was not allowed to witness any part of it, nor were reporters provided with an account. There is no official US government record of the intimate dinner conversation because no American official other than the President was involved.

"Pretty much everyone at the dinner thought this was really weird, that here is the President of the United States, who clearly wants to display that he has a better relationship personally with President Putin than any of us, or simply doesn't care," said Mr Ian Bremmer, president of the Eurasia Group, a New York-based research and consulting firm, who said he had heard directly from attendees.

The encounter occurred more than midway through the lengthy dinner, when Mr Trump left his chair and approached Mr Putin. It was described to Mr Bremmer by guests as lasting about an hour.

Mr Sean Spicer, the White House press secretary, said Mr Trump had described the exchange with Mr Putin as purely social, and as lasting far less than an hour.

In a separate statement, the White House said the two presidents had spoken through the Kremlin's interpreter as the American translator with Mr Trump did not speak Russian.

Experts in US-Russia relations said such an encounter was a concern because of its length, which suggested a substantive exchange, and because there was no note taker or national security or foreign policy aide present.

The Trump administration is struggling to improve its relationship with Russia while under pressure from multiple investigations into possible ties between Mr Trump's campaign and Moscow.

NYTIMES, BLOOMBERG