The ex-Labour leader hit back after being branded "a complete liar" by Michael Wolff, who recently penned an explosive book about the US President.
The row stems from claims made by Mr Wolff in "Fire And Fury: Inside the Trump White House" that Mr Blair told Jared Kushner, Mr Trump's son-in-law and key adviser, that Britain might have spied on the Trump campaign and even Mr Trump himself.
Mr Wolff also suggested that Mr Blair had been keen on a job as a Middle East peace envoy with Mr Trump's White House.
The ex-premier denied the claims at the time of the book's publication earlier this year.
But, asked about Mr Blair's denial on the BBC's Andrew Marr Show on Sunday, Mr Wolff said: "I sat in the White House on the couch listening - I wasn't supposed to overhear this but they were standing right there - with Tony Blair and Jared Kushner standing not 15 feet in front of me.
"With Tony Blair, let me choose my words carefully, sucking up to Jared Kushner."
He added: "I have to say Tony Blair is a complete liar."
Mr Wolff's latest claims led Mr Blair to again repeat his insistence the claims are a "complete fabrication".
A statement from the Tony Blair Institute said: "Michael Wolff has never been present at any conversation between Jared Kushner and Mr Blair.
"He neither sought such a role from Jared Kushner nor was offered one.
"And we note that many people have had the same experience with Michael Wolff."
Source : https://news.sky.com/story/tony-blair-hits-back-after-being-branded-complete-liar-by-trump-book-author-michael-wolff-11267733499