Letters from the 1980s have been released, in which MP Geoffrey Dickens called for then-Home Secretary Leon Brittan to ban a pro-paedophilia group.
In 1983, The Conservative MP wrote he "would not rest" until the Paedophile Information Exchange was outlawed.
Lord Brittan wanted to see if existing laws proved adequate first.
Before his death in January this year, the Tory peer had faced questions over his handling of child abuse allegations during his time in office.
The letters between Lord Brittan and Mr Dickens, who died in 1995, have been made public after a Freedom of Information request from the BBC.
Notes of a meeting at which Mr Dickens urged the peer to ban the exchange (PIA) have also been released.
At the heart of the controversy facing Lord Brittan before he died was a so-called dossier on alleged high-profile paedophiles handed to him by Mr Dickens, a long-standing campaigner against child abuse.
Lord Brittan always insisted the proper procedures had been followed.
The BBC submitted the FOI request for these documents to be made public last summer, when the story of the "Dickens' dossier" made national headlines.
In the first letter, dated 17 August 1983, Mr Dickens, then MP for Littleborough and Saddleworth, asked for PIE to be banned, and called for the law protecting children from sexual abuse to be toughened up.
Mr Dickens wrote: "I shall not rest until we outlaw such organisations and it will not embarrass me to put our front bench under tremendous pressure on this subject because this time I shall carry the House of Commons and the country with me - be in no doubt."
On 23 November 1983, Mr Dickens met Lord Brittan, junior Home Office minister David Mellor and three others, believed to be civil servants.
On the question of banning PIE, the official taking the meeting notes wrote that the home secretary was of the view that it would be important to see if existing laws proved adequate first.
Lord Brittan is also said to have raised "the fundamental objection to banning an organisation that if members of the organisation were doing a mischief, it was the mischief which ought to be banned, not the organisation".
Mr Dickens introduced a Paedophilia (Protection of Children) Bill to make membership of PIE and similar organisations illegal in June 1984.
The Bill did not proceed but PIE is believed to have disbanded later that year.
The meeting minutes also confirm that Mr Dickens handed over two letters, one of which concerned allegations of paedophilia in the Civil Service.
In response Lord Brittan is reported to have told Mr Dickens that "he was prepared to ensure that any evidence of such activities which had substance to them would be investigated".
"He would certainly ensure that the letters which Mr Dickens had handed him were looked into."
Mr Dickens also reiterated calls for the law to be toughened up on dealing with pornographic material involving children.
According to the meeting notes, Lord Brittan is said to have considered the law on incitement of sexual activities with children to be "not so clear" and a matter he would "want to look at" in the future.
Lord Brittan also advised Mr Dickens on what to say to the press about their conversation.
Following the meeting, Mr Dickens wrote what appears to be a cover note to the home secretary on 17 January 1984, enclosing more cases for investigation and enquiring about the progress made on the cases previously handed over.
He also thanked Lord Brittan for his "splendid support".
An independent review of Home Office files from 1979-1999, produced in April 2013, confirmed that the Home Office did receive information from Mr Dickens in November 1983 and January 1984 about alleged child abuse.
The subsequent Wanless Inquiry into the Home Office's handling of child sexual abuse claims in the 1980s failed to uncover the "dossier".
The material obtained by the BBC was examined during the course of these investigations but was not made public.