Russian President Vladimir Putin said that if Moscow receives an official request from Mueller investigation, then Russian will question them according to the treaty dating back to the nineties.

Under that treaty, officially titled the 'Treaty between the Government of the United States of America and the Russian Federation on Mutual Legal Assistance in Criminal Matters,' Putin said the probe "could send an official request to Russia so that we hold an investigation or questioning of those individuals and our prosecutor general offices will look into it, hold the questioning, and then send all those materials to the US."

Just three days before the summit, the probe led by special council Robert Mueller indicted twelve Russian intelligence officers for hacking the Democratic party and the Hillary Clinton campaign, the US Department of Justice announced, adding that no Americans were involved and no votes affected.

"We can even make another step forward, we can also invite US official representatives - including members of the Mueller probe - to be present during the questioning," Putin said.

Trump called Putin's offer to help with the investigation "incredible."

US President Donald Trump has stated that the Mueller probe is a "disaster" for the US.

Putin called claims of meddling in the presidential election "absurd," and requested a single fact to prove the allegation.

"I think that the probe is a disaster for our country, I think it's kept us apart, it's kept us separated, there was no collusion at all, everybody knows it," Trump said.

Russia would, however, expect for such cooperation to be a "two-way street," meaning the US would allow Moscow "to question those officials including from the security services that we believe are behind illegal activities on the territory of the Russian Federation with the presence of our investigators," Putin said.

Putin proceeded to speak about the Hermitage Capital case, noting that according to Russian investigators, business associates of CEO William Browder illegally earned more than $1.5 billion.

“They didn't pay a cent of taxes but they transferred the money to the US and they also donated $400 million to the Clinton campaign – $400 million. They might have done it legally, but they earned that money illegally,” Putin said.

The Russian president stated that there is evidence to believe that some within the US security services helped Browder to “conduct those illegal transfers.”

Browder, the CEO of Hermitage Capital, made billions during Russia’s ‘shock therapy’ in the ‘90s. In December 2017, a Moscow court sentenced Browder to nine years in prison in absentia for tax fraud. He was also found guilty of tax evasion in a separate case from 2013. Hermitage has repeatedly been investigated for tax fraud.