US Vice President Joe Biden said top intelligence leaders told him and President Barack Obama they felt obligated to inform them about uncorroborated allegations about President-elect Donald Trump, out of concern the information would become public and catch them off-guard.

In an interview, Biden said neither he nor Obama asked US intelligence agencies to try to corroborate the unverified claims that Russia had obtained compromising sexual and financial allegations about Trump.

"I think it's something that obviously the agency thinks they have to track down,'' Biden said. He added later, "It surprised me in that it made it to the point where the agency, the FBI thought they had to pursue it.''

INTS KALNINS/REUTERS Biden said neither he nor Obama asked US intelligence agencies to try to corroborate the unverified claims.

In the hourlong session with The Associated Press and other news outlets, the vice president was sharply critical of Trump for publicly disparaging intelligence officials, saying Trump was damaging US standing and playing into Russia's hands. He also took umbrage at Trump's comments accusing intelligence agencies of allowing the information to leak publicly and drawing a comparison to "living in Nazi Germany.''

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CARLOS BARRIA/REUTERS "Neither the president nor I asked for any detail,'' Biden said of the dossier.

"The one thing you never want to invoke is Nazi Germany, no matter what the circumstances,'' Biden said. "It's an overwhelming diversion from the point you're trying to make.''

Incoming president, Donald Trump, rounded on news organisations for publishing the dossier.

Biden said that in the briefing he and Obama received from Director of National Intelligence James Clapper and others, there were "no conclusions drawn'' from the uncorroborated dossier, which was produced in August and then released publicly this week by the media.

Biden said it was "totally ancillary'' to the purpose of the meeting, which was to brief Obama on a report he ordered documenting Russian interference in the US campaign.

"As a matter of fact, the president was like, 'What does this have anything to do with anything?''' Biden said. He said intelligence leaders responded by saying "Well, we feel obliged to tell you, Mr. President, because you may hear about it. We're going to tell him,'' referring to Trump.

SHANNON STAPLETON / REUTERS Donald Trump has denied the claims.

Biden said intelligence leaders told him and Obama that they couldn't say whether or not the allegations were true or untrue. He said there was "hardly any discussion'' about the allegations in the briefing.

"Neither the president nor I asked for any detail,'' Biden said. But he added of the dossier: "I've read everything.''

Trump has vehemently denied the allegations included in a dossier about close coordination between Trump's inner circle and Russians. The dossier also included unsubstantiated claims about unusual sexual activities by Trump, attributed to anonymous sources. Trump has denied them.

The FBI has been working to corroborate the details in the dossier, although it's unclear how long that investigation has been running or how many resources are assigned. FBI Director James Comey has declined even to acknowledge the investigation publicly in line with FBI protocol.

The dossier was compiled by a former Western intelligence operative and had been circulating among news organisations and intelligence agencies in Washington for months. Its existence became known publicly following reports the intelligence community had briefed Trump on the dossier.

In the interview, Biden criticised Trump's rocky relationship with intelligence officials. The president-elect has publicly challenged their assessment about Russia's role in the election and suggested they have skewed evidence. Trump has received the President's Daily Brief, the highest-level intelligence document produced in the United States, a few times but has insisted he doesn't need it daily and suggested he knows more than intelligence leaders.

Biden said it would be a "genuine tragedy'' if Trump refused the daily intelligence briefing presidents traditionally receive.

To illustrate his point, Biden took out the black tablet computer he uses to read his daily briefing and showed it to reporters as he sat next to a crackling fireplace in his office, just steps from the Oval Office. He said it is password-protected and includes a feature he uses to ask questions about the intelligence that are responded to the same day.

Biden said at least five foreign leaders have already contacted him expressing concern over Trump's second-guessing of US intelligence agencies.

"It is really very damaging in my view to our standing in the world for a president to take one of the crown jewels of our national defense and denigrate it,'' Biden said. "It plays into, particularly now, the Russian narrative that America doesn't know what it's doing.''

After nearly half a century in public office, Biden will exit the national stage next Friday, although he plans to stay active in Democratic politics and work on policy issues at a pair of institutes he's developing at the University of Delaware and the University of Pennsylvania. He also plans to continue with the cancer "moonshot'' effort he launched after his son died.

Biden was awarded the Presidential Medal of Freedom by Obama on Thursday (Friday NZ time).

Biden was full of praise for his successor, Vice President-elect Mike Pence. He said he's been sending Pence memos with his advice on how to handle certain relationships, such as with Iraqi and Ukrainian leaders, and on "the things that could explode most easily.''

He said Pence had been receptive to his advice but had less time these days to speak to Biden due to the heavy role he's playing in setting up Trump's administration. Biden said he's made his national security adviser, Colin Kahl, available to Pence but hoped Pence would quickly name a national security adviser of his own.

"It would be better if they had been in a better position where he actually had somebody that Colin could sit down with every morning,'' Biden said.﻿