(CNN) Excerpts from journalist Michael Wolff's forthcoming book "Fire and Fury: Inside the Trump White House" detail salacious allegations and explosive insight into background conversations thought to have shaped US President Donald Trump's first year in office.

Although the book isn't available until Friday, excerpts published this week in a number of media outlets shed new light on the Trump administration's early days. CNN has not independently verified all of the details in Wolff's book.

UK: Blair's secret Kushner meeting

In his book, Wolff claims that former British Prime Minister Tony Blair held a secret meeting with Trump's senior advisor and son-in-law Jared Kushner in February 2017. He writes that Blair told Kushner it was possible the UK may have spied on campaign officials or even Trump himself, according to excerpts published in the Times of London and the Guardian, which obtained a copy of the book.

Blair flatly denied the claims.

"I have never had such conversations in the White House or outside of the White House, with Jared Kushner or with anybody else," Blair told BBC Radio 4's "Today" program on Thursday.

Blair also said that he had spoken with Kushner about the Middle East peace process but that he had not been fishing for a job within the administration -- nor was he offered one.

The UK intelligence agency GCHQ -- the equivalent of the US National Security Agency -- reiterated its denial of any spying claims.

"As we have previously stated, allegations that GCHQ was asked to conduct 'wire-tapping' against Trump Tower are nonsense. They are utterly ridiculous and should be ignored," a GCHQ spokesperson said on Thursday.

Allegations of UK spying first arose during a press briefing in May, when then-White House press secretary Sean Spicer read out a Fox News report that said that GCHQ had spied on Trump.

Prime Minister Theresa May's office first called the claims "ridiculous" and said they "should be ignored," adding that they had "received assurances that these allegations won't be repeated."

RUSSIA: 'Putin couldn't give a s*** about him'

Over a late-night dinner between ousted Fox News head Roger Ailes and then-White House chief strategist Steve Bannon on January 3, 2017 -- two weeks before the inauguration -- Wolff writes that talk of Russia was on the menu.

"What has he gotten himself into with the Russians?" Ailes asked Bannon during the meal, which was organized by mutual friends at a townhouse in downtown New York, according to Wolff.

"Mostly, he went to Russia and he thought he was going to meet [President Vladimir] Putin. But Putin couldn't give a s*** about him. So he's kept trying," Bannon said, according to Wolff's New York Magazine story , which was adapted from his forthcoming book.

Bannon has yet to respond to CNN's request for comment.

The White House released a statement from the President on Wednesday, who said that Bannon had "lost his mind" after he was ousted from the White House.

Trump also accused Bannon, once his closest ally, of cozying up to reporters and wasting time inside the White House leaking "false information." Bannon has long called the mainstream media the "opposition party."

JERUSALEM: Trump 'totally onboard' with embassy move

At the same New York dinner during the presidential transition, Wolff writes that Bannon announced the incoming administration's immediate plan to move the US embassy to Jerusalem.

"Day one we're moving the US Embassy to Jerusalem. Netanyahu's all-in. Sheldon is all-in," Bannon allegedly said, referring to billionaire donor Sheldon Adelson who, one month later, said Trump was likely to be "the best president for Israel ever."

Regarding a Middle East peace plan, Bannon also allegedly said: "We know where we're heading on this ... Let Jordan take the West Bank, let Egypt take Gaza. Let them deal with it. Or sink trying."

Ailes asked, "Where's Donald on this?" according to Wolff's account.

"He's totally onboard," Bannon allegedly replied.

In December, Trump formally recognized Jerusalem as Israel's capital and announced plans to relocate the US Embassy there, overturning decades of US policy and sparking condemnation from 128 member states at the United Nations.

CHINA: 'We don't get China right, we don't get anything right'

Wolff writes that Bannon was keen to bring up China's future global role during the dinner with Ailes, referring to the superpower as "the real enemy" and the "first front in a new Cold War."

"China's everything. Nothing else matters. We don't get China right, we don't get anything right. This whole thing is very simple. China is where Nazi Germany was in 1929 to 1930. The Chinese, like the Germans, are the most rational people in the world, until they're not. And they're gonna flip like Germany in the '30s. You're going to have a hypernationalist state, and once that happens, you can't put the genie back in the bottle," Bannon allegedly said.

On Wednesday, White House press secretary Sarah Sanders dismissed the book in its entirety.

"This book is filled with false and misleading accounts from individuals who have no access or influence with the White House. Participating in a book that can only be described as trashy tabloid fiction exposes their sad desperate attempts at relevancy," she said.