Donald Trump’s eldest son on Monday admitted meeting a Russian lawyer to get dirt on his father’s 2016 rival Hillary Clinton, thrusting the White House deep into another Russia-related scandal.

Trump junior confirmed reports that he was on the trail of damaging information on the Democrat vying to become America’s first female president, when he met Natalia Veselnitskaya in June 2016.

“Obviously, I’m the first person on a campaign to ever take a meeting to hear info about an opponent,” Trump’s son said in a tweet, claiming that it “went nowhere” but he “had to listen.”

The FBI and Congress are investigating whether the Trump campaign colluded with Russia to influence the 2016 presidential vote.

US intelligence agencies have concluded that Russian President Vladimir Putin approved a mass effort to tilt the election in Trump’s favor, including hacking and leaking embarrassing emails from Democrats.

A spokeswoman for the Trump Organization, Amanda Miller, confirmed to AFP that Donald Trump Jr. had hired attorney Alan Futerfas to represent him in the widening Russian meddling investigation, amid calls -- including from senior members of the US Congress -- that he provide testimony in the case.

The New York Times reported that Paul Manafort and Jared Kushner, two of Trump’s most trusted campaign officials, were also at the meeting last year.

Veselnitskaya is not well known in Russia, but represented the son of a senior Russian official who was involved in a major fraud probe that had international repercussions.

In a statement to the Times, the younger Trump said the lawyer “stated that she had information that individuals connected to Russia were funding the Democratic National Committee and supporting Mrs Clinton.”

“It quickly became clear that she had no meaningful information,” he said, adding that the lawyer then began discussing the adoption of Russian children by American couples under a program Putin had suspended.

The meeting took place at a pivotal point in the 2016 campaign, after Trump had shocked Republicans with a string of primary victories and Clinton had all-but secured the Democratic nomination.

US officials have sought to distance the president himself from the encounter.

“The president was not aware of and did not attend the meeting,” Mark Corallo, a spokesman for President Trump’s private lawyer, told AFP.

White House spokeswoman Sarah Huckabee Sanders said Trump had only learned of the meeting “in the last couple of days.”

Donald Trump junior’s meeting has already drawn the attention of Congressional investigators.

“Our intelligence committee needs to interview him and others who attended the meeting,” said Republican Senator Susan Collins.

A spokesperson for Kushner did not respond to request for comment.

The Kremlin said it “did not know who” Veselnitskaya was. “We can’t be aware of all the meetings Russian lawyers have abroad,” said spokesman Dmitri Peskov.

President Trump has repeatedly decried allegations of collusion as “fake news” and equivocated about whether Russia tried to interfere in the election.

During a meeting with Putin on Friday on the margins of the G-20 summit in Germany, Trump raised the issue of election interference before turning to other subjects.

“I strongly pressed President Putin twice about Russian meddling in our election,” Trump later said. “He vehemently denied it. I’ve already given my opinion.”

That meeting in Hamburg is raising yet more Russia-related problems for the White House.

Scrambling for concrete victories to take away from the controversial two-hour-plus sit-down, the White House hailed deals establishing a joint “cyber unit” and a cease-fire in southern Syria.

Treasury Secretary Steven Mnuchin claimed Trump was “brilliant” during the meeting and said the cyber unit would “make sure that Russia and nobody else interferes in any democratic elections.”

No details of the plan were provided, however, and it appeared to quickly unravel when Trump himself questioned if it would come into effect.

“The fact that President Putin and I discussed a Cyber Security unit doesn’t mean I think it can happen. It can‘t -- but a ceasefire can, & did!” he tweeted.

The internationally brokered cease-fire in southern Syria has brought quiet to most of the three provinces covered -- Daraa, Quneitra and Sweida.

But the Syrian Observatory for Human Rights, a Britain-based monitor, reported a government assault on Sweida province, just 24 hours into the truce, in addition to scattered violations recorded elsewhere.

Syrian state media claimed the Sweida assault was targeted against the Islamic State group. (AFP)