US President Donald Trump has defended his son as “open, transparent and innocent” after the younger Trump’s Fox News interview, and lashed the Russia controversy engulfing his son as “the greatest witch hunt in political history.”

On Tuesday, Mr Trump Jr released a series of emails that showed he had eagerly agreed to meet with a Russian government lawyer during the presidential campaign, who might have damaging information about Democratic rival Hillary Clinton.

“My son Donald did a good job last night,” Mr Trump wrote on Twitter, referring to his son’s Tuesday television interview.

“He was open, transparent and innocent. This is the greatest Witch Hunt in political history. Sad!”

The emails, released by Donald Trump Jr, are the most concrete evidence yet that campaign officials welcomed Russian help to win the election.

The messages show the younger Trump was open to the prospect of “very high-level and sensitive information” from a Russian lawyer that a go-between described as “part of Russia and its government’s support for Mr Trump” before a meeting on June 9, 2016.

“If it’s what you say I love it,” Trump Jr responded.

He released the messages on Twitter after The New York Times said it planned to write about them and sought comment from him.

The messages indicate Mr Trump’s campaign manager at the time, Paul Manafort, and son-in-law Jared Kushner, now a top White House adviser, also planned to attend the meeting Russian lawyer Natalia Veselnitskaya, who denies having Kremlin ties.

Donald Trump Jr said Ms Veselnitskaya did not provide damaging information about Mrs Clinton and instead sought to discuss Russian sanctions.

“In retrospect, I probably would have done things a little differently,” Donald Trump Jr said on Fox News. “For me, this was opposition research.”

Meanwhile, Russian Foreign Minister Sergei Lavrov said it was “wild” that Donald Trump Jr was being blamed for meeting the Russian lawyer.

“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.”

Meanwhile, Mr Trump has tried to downplay the controversy and deflect the heat currently on the White House, with a business-as-usual post on Twitter.

The W.H. is functioning perfectly, focused on HealthCare, Tax Cuts/Reform & many other things. I have very little time for watching T.V.

— Donald J. Trump (@realDonaldTrump) July 12, 2017