Ministers and the intelligence services will be able to cover up sensitive information relating to the state's complicity in torture and secret rendition, under controversial plans likely to be included in the Queen's Speech in May.

Sources at the Ministry of Justice say the plans, first outlined in a green paper in October last year, are likely to be included in a justice bill in the next session of parliament in a move that critics say will fundamentally undermine Britain's tradition of open justice.

The plan could mean that so-called closed material procedures – in which secret evidence is withheld from the claimant and the press in a closed court – would be introduced more widely into civil law. This would allow the government or its agencies to defend serious allegations knowing that damaging information would never emerge.

Examples of cases which opponents say could be held under such procedures include those where torture victims sue the government, where inquests are held relating to soldiers killed by friendly fire, or where actions are lodged alleging police negligence.

The claimants would be represented by special advocates who would be barred from discussing the evidence with them. The government is pushing ahead despite the fact that out of 69 currently appointed special advocates, 57 have signed a response hitting out at the proposal – saying there is no reason to justify such sweeping changes.

Shami Chakrabarti, director of Liberty, which will launch a campaign against the plans on Tuesday, said: "What bitter irony if the government's answer to the worst excesses of the 'war on terror' were an even bigger, darker cloak over the secret state. If these proposals represent the agencies' response to concerns about complicity in torture, they are surely either unnecessary or dangerous.

"If flirtation with extraordinary rendition was an aberration after 9/11, why wreck the whole civil justice?"

The Equality and Human Rights Commission, in its response to the green paper, has said that "closed material procedures can never be completely fair and are likely to violate… the right to a fair trial."

The organisation Reprieve, which promotes the rule of law around the world, says that the government plan, if in force at the time, would have meant the torture of British resident Binyam Mohamed would never have been made public. Binyam Mohamed spent just under seven years in custody – four of those at the US's Guantanamo Bay camp in Cuba.

He and six other men who claim they were tortured and that the British government did nothing to help them received millions of pounds in compensation in November 2010.

Reprieve says the extension of closed material procedures across civil courts "risks creating a parallel system of secret justice, operating in the shadows and undermining Britain's centuries-old tradition of open justice.

"It will replace the current system, under which the government's national security concerns are balanced against right and liberties of the individual with one in which proceedings are strongly skewed in favour of the state."

A response to the green paper from Guardian News and Media, owners of this newspaper, says Kenneth Clarke's proposal would have a serious impact on the judicial process, court reporting and public interest journalism. Closed hearings, secret evidence and secret pleadings and judgments will result in the indefinite removal of information from the public domain.