Watergate reporter Carl Bernstein has slammed Donald Trump's former spokesman for dismissing the ongoing investigation into Russian links to the election campaign.

Appearing on CNN, Trump surrogate Jason Miller said there has been "not one piece of evidence" linking the campaign to Russia.

He was asked specifically about a meeting between Blackwater founder Erik Prince and a Russian close to President Vladimir Putin, which US, European and Arab officials said was part of an apparent effort to establish a back-channel line of communication between Moscow and then President-elect Trump.

In response, Mr Miller said: “Number one... Mr Prince had no role with the campaign, no role with the administration.”

He added: “If the fundamental point of this investigation is to get to some supposed coordination between the campaign and some foreign government, then immediately upon leaving that meeting, Mr. Prince would have had to have walked out, gotten into his Blackwater time machine, gone back months and then hatched some devious plot to influence the election."

He went on to add: "At some point here, this is just a wild goose chase."

Mr Bernstein then jumped in, saying: “Let me just add one thing to contradict that.

The controversial orders Donald Trump has already issued Show all 9 1 /9 The controversial orders Donald Trump has already issued The controversial orders Donald Trump has already issued Trump and the media White House Press Secretary Sean Spicer takes questions during the daily press briefing Getty Images The controversial orders Donald Trump has already issued Trump and the Trans-Pacific Partnership Union leaders applaud US President Donald Trump for signing an executive order withdrawing the US from the Trans-Pacific Partnership negotiations during a meeting in the Roosevelt Room of the White House in Washington DC. Mr Trump issued a presidential memorandum in January announcing that the US would withdraw from the trade deal Getty The controversial orders Donald Trump has already issued Trump and the Mexico wall A US Border Patrol vehicle sits waiting for illegal immigrants at a fence opening near the US-Mexico border near McAllen, Texas. The number of incoming immigrants has surged ahead of the upcoming Presidential inauguration of Donald Trump, who has pledged to build a wall along the US-Mexico border. A signature campaign promise, Mr Trump outlined his intention to build a border wall on the US-Mexico border days after taking office Getty Images The controversial orders Donald Trump has already issued Trump and abortion US President Donald Trump signs an executive order as Chief of Staff Reince Priebus looks on in the Oval Office of the White House. Mr Trump reinstated a ban on American financial aide being granted to non-governmental organizations that provide abortion counseling, provide abortion referrals, or advocate for abortion access outside of the United States Getty Images The controversial orders Donald Trump has already issued Trump and the Dakota Access pipeline Opponents of the Keystone XL and Dakota Access pipelines hold a rally as they protest US President Donald Trump's executive orders advancing their construction, at Columbus Circle in New York. US President Donald Trump signed executive orders reviving the construction of two controversial oil pipelines, but said the projects would be subject to renegotiation Getty Images The controversial orders Donald Trump has already issued Trump and 'Obamacare' Nancy Pelosi who is the minority leader of the House of Representatives speaks beside House Democrats at an event to protect the Affordable Care Act in Los Angeles, California. US President Donald Trump's effort to make good on his campaign promise to repeal and replace the healthcare law failed when Republicans failed to get enough votes. Mr Trump has promised to revisit the matter Getty Images The controversial orders Donald Trump has already issued Donald Trump and 'sanctuary cities' US President Donald Trump signed an executive order in January threatening to pull funding for so-called "sanctuary cities" if they do not comply with federal immigration law AP The controversial orders Donald Trump has already issued Trump and the travel ban US President Donald Trump has attempted twice to restrict travel into the United States from several predominantly Muslim countries. The first attempt, in February, was met with swift opposition from protesters who flocked to airports around the country. That travel ban was later blocked by the Ninth Circuit Court of Appeals. The second ban was blocked by a federal judge a day before it was scheduled to be implemented in mid-March SANDY HUFFAKER/AFP/Getty Images The controversial orders Donald Trump has already issued Trump and climate change US President Donald Trump sought to dismantle several of his predecessor's actions on climate change in March. His order instructed the Environmental Protection Agency to reevaluate the Clean Power Plan, which would cap power plant emissions Shannon Stapleton/Reuters

"I know beyond any doubt, from people who worked in the Trump campaign on national security areas, that indeed Erik Prince was a part of the campaign, did see president-elect Trump—“

He was then interrupted by Mr Miller, who asked: "Who said that?"

Mr Bernstein declined to name his source, saying: "I'm not gonna say who said it. But believe me, I think you have the ability, sir, to go find out."

Mr Miller said he never heard Mr Prince's name come up during the campaign.

Donald Trump says he wants to be president of the US, not the world

The legendary Watergate reporter, a persistent critic of Mr Trump, replied: "OK well I suggest you go back and talk to those who were involved in the national security area of the campaign and of the transition and you will find as I and many other journalists have that Erik Prince indeed had a role, talked to a number of people including the President-elect and indeed bragged about that role.

He added: "I think this idea that to cut what is really true out of the story in a defence way is hurting everybody's ability to find out what the truth is here.