Donald Trump has condemned unsubstantiated reports of "compromising" information about his behaviour in Russia as "fake news".

The row overshadowed outgoing Barack Obama's emotional valedictory speech in his home city of Chicago, when he played on the phrase that has became a signature of his presidency: "Yes we can," he said. "Yes we did." 

Once again, Trump succeeded in capturing the headlines. 

In a tweet about the allegations, he raged in capital letters: "FAKE NEWS - A TOTAL POLITICAL WITCH HUNT!"

He also tweeted a photograph of his passport, saying he had never been to Prague in his life:

And he singled out Buzz Feed for special attack for running one of the documents:

The classified documents that the heads of four US intelligence agencies presented last week to President-elect Donald Trump included claims that Russian intelligence operatives have compromising information about him.

Ttwo US officials told Reuters the claims, which one called "unsubstantiated," were contained in a two-page memo appended to a report on Russian interference in the 2016 election.

It is understood that the Federal Bureau of Investigation and other agencies are looking into the accuracy of the claims.

Additional reporting by Reuters.