Ed Miliband says he urged Gordon Brown to sack Damian McBride over concerns the spin doctor was briefing against senior Labour colleagues.
Mr McBride, who worked for Mr Brown, admits in a new book that he leaked stories to smear the ex-PM's opponents.
Mr Miliband - who worked with Mr McBride at the Treasury - said he had been "worried" about his activities.
And he had urged Mr Brown to get rid of the spin doctor, the Labour leader said in an interview with Andrew Marr.
In his memoirs, being serialised in the Daily Mail, Mr McBride confesses to leaking details about the personal lives of Labour ministers seen as a threat to Gordon Brown's ambitions to replace Tony Blair as prime minister.
The revelations include claims that Mr McBride:
- held a "black book" of stories about former Home Secretary Lord Reid, who resigned from the cabinet to avoid damaging newspaper allegations
- "orchestrated a briefing war" between Charles Clarke and one of Mr Blair's advisers, leading to the ex-home secretary's sacking
- leaked a damaging story to the News of the World about then Health Minister Ivan Lewis involving a female civil servant in his private office
- accused shadow foreign secretary Douglas Alexander of being "cold-blooded" when he insisted sister and fellow Labour politician Wendy Alexander would have to resign over a donation
- was asked to intervene in the 2010 Labour leadership contest - in which Mr Brown privately backed Ed Miliband over Ed Balls
He suggests that Mr Brown was aware of his methods and had given his unspoken approval.
Mr McBride has also attempted to implicate Mr Miliband in the spin culture that prevailed in parts of the Labour government, suggesting he might "have problems" if email exchanges between Mr Miliband and spin doctor Derek Draper came to light.
Mr Miliband has insisted that although he knew negative briefings were going on, he did not approve of them.
He told the BBC's Andrew Marr programme he found such behaviour "reprehensible" and stressed that there was no place for it in his Labour Party.
"People who know me will know I haven't engaged in the factionalism and briefing - and that's not my style of politics," he said.
He has previously said he had raised concerns about Mr McBride's behaviour with Mr Brown but went further in his Marr interview, saying he had urged the then chancellor to get rid of him.
'Kicking your star players'
Speaking on the Sunday Politics Show, Tony Blair's former director of communications Alastair Campbell said Mr McBride's actions had made it very difficult for him to do his job as Labour's director of communications and strategy as he was "trying to hold the whole thing together".
He said he used to challenge Mr Brown about him, as did Mr Miliband.
Mr Campbell added that it was like being in a football team where on the pitch, "you had your own players going around and kicking your star players".
"That's why I'm still angry about it because I think they helped usher in a Conservative government and if we'd stuck together - I know it's a big if - if we'd stuck together I think we'd still be there," he added.
Shadow home secretary Yvette Cooper, whose husband Ed Balls was a key Brownite, said Mr McBride was "out of control".
Speaking on Sky News' Murnaghan programme, she said: "It is something that happened some years ago, but I think it's a sign of how much the Labour Party has changed.
"The very different climate, the very different way in which Ed Miliband is managing things and operating things now, that's a good thing, we don't want to go back to the navel gazing of the past."
Shadow business secretary Chuka Umunna said of the ex-spin doctor: "He's a relic from the past. There is no place for that kind of nasty, vile politics in Britain today. I am glad we've seen the back of him."
He added that he was at a shadow cabinet meeting where Mr Miliband was "very clear he will not tolerate any of that kind of behaviour".