US President Donald Trump has said he was unaware of his son Donald Trump Jr's meeting last year with a Russian lawyer at the heart of a White House controversy.

Mr Trump told Reuters he only learned of it a couple of days ago.

Asked if he knew that his son was meeting with the Russian lawyer Natalia Veselnitskaya in June last year, Trump said in a White House interview: No, that I didn’t know until a couple of days ago when I heard about this.

Mr Trump Jr. eagerly agreed to meet the woman he was told was a Russian government lawyer who might have damaging information about Democratic rival Hillary Clinton as part of Russia's official support for his father's presidential election campaign, according to emails the son released yesterday.

In the interview, Mr Trump said he did not fault his son for holding the meeting.

"I think many people would have held that meeting," the president said.

The emails were the most concrete evidence that Trump campaign officials welcomed Russian help to win the 2016 election, a subject that has cast a cloud over Mr Trump's presidency and prompted investigations by the US Justice Department and Congress.

In today’s interview, Mr Trump also said he directly asked Russian President Vladimir Putin if he was involved in what US intelligence says was Russian meddling in the presidential campaign and that Mr Putin had insisted he was not.

Mr Trump said he spent the first 20 or 25 minutes of his more than two-hour meeting with Mr Putin last Friday in Germany on the subject of election meddling.

"I said, did you do it? And he said no, I did not. Absolutely not. I then asked him a second time in a totally different way. He said absolutely not," Mr Trump said.

Earlier Mr Trump defended his eldest son as "innocent" amid the growing controversy over the meeting.

The Kremlin has insisted it was in no way linked to a meeting between Donald Trump Jr son a Russian lawyer at the heart of a political firestorm.

"We have already said that we are absolutely not familiar with this whole story," said Kremlin spokesman Dmitry Peskov.

Russian Foreign Minister Sergei Lavrov said it was "wild" that Mr Trump Jr was blamed for meeting a Russian lawyer that emails show might have had damaging information about Hillary Clinton last year.

"I learned with surprise that a Russian lawyer, a women, is being blamed and Trump's son is being blamed for meeting. For me, this is wild," Mr Lavrov said during a visit to Brussels.

"Because when any person speaks to a lawyer, what problem or threat could be there? I didn't know about this, I learned about it from television."

Mr Trump Jr has said he did not tell his father about meeting Natalia Veselnitskaya during the 2016 campaign, after the talk failed to yield compromising information about Mrs Clinton.

"No. It was just a nothing. There was nothing to tell," Donald Trump Jr told the Fox network's 'Hannity' programme.