The level of British collusion with loyalist paramilitaries was “truly shocking” but it never justified the actions of the IRA, the SDLP leader Dr Alasdair McDonnell told his party’s annual conference in Armagh today.

As the Richard Haass talks on the past, flags and parades comes to its crucial stages Dr McDonnell said it was critical that the legacy of the Troubles was addressed on an ethical basis.

“Central to that healing process is uncovering the truth about all killings and securing answers and a measure of justice for all victims and survivors,” he said in the Armagh City Hotel conference centre.

“That includes getting to the truth of the appalling British State collusion with loyalist murder gangs that takes on a more sinister character with every new disclosure,” he added in relation to the recent collusion disclosures in the book Lethal Allies.

“That collusion is truly shocking but it never ever justified a single IRA atrocity. And the IRA must come clean and tell the truth as well,” he said.

“And no IRA atrocity can ever justify unionist politicians dismissing collusion. Such talk is not just insulting to victims and survivors. It’s insulting to the hundreds of honest RUC officers who hunted down loyalist killers as well as IRA killers and brought them to justice,” he added.

Dr McDonnell addressing 400 delegates just six months ahead of the European and council elections said the SDLP was “ready for the electoral battle next May”.

“With a little more help from each of you we will confound the critics and baffle the cynics,” he exhorted.

Dr McDonnell said people feel “very badly let down” by the two main Northern Ireland parties. “The DUP and Sinn Féin are the parties of disappointment, false promise, poor government, bad politics - and no results. They have had their chance and they have failed the test,” he said.

Dr McDonnell said “after thirty years of murder, abuse, and suffering our battered society is crying out for healing and reconciliation”. The SDLP’s core values were reconciliation, social justice and prosperity which were “central to rebuilding faith in politics, and trust in politicians and delivering worthwhile benefits”.

He defended the SDLP’s decision to support limiting the flying of the British union flag over Belfast City Hall which triggered disorder from last Christmas. “As Irish nationalists we make no apology for regarding the tricolour as our national flag. We believe that the Irish tricolour, emblems, symbols, and language should be given parity of esteem,” he said.

Dr McDonnell added, “Last December, Belfast City Council arrived at a sensible compromise, to fly the union flag on designated days, a decision that was supported by the SDLP. It is unfortunate that unionists cannot do compromise.”

He said there must be a comprehensive approach to addressing matters of political and cultural identity such as emblems, symbols, languages and memorabilia. “The British and Irish Governments must be the co-guarantors of any agreement emerging from the Haass Talks .

They must be fully engaged in any outcomes and exert the power and influence for a sustainable solution,” he said.

“The needs of victims and survivors must have priority in this process especially the voices of those victims that have been silent for too long such as those families of the Disappeared profiled so movingly in a recent documentary,” he added.

Dr McDonnell called on the Northern executive and the British and Irish governments to support the creation of a formal “prosperity process, a mini Marshall Plan” to underpin politics and the peace process in Northern Ireland.

In a speech later today former leader Margaret Ritchie called for the SDLP to go into opposition in the Assembly. She said that the “two-party” SF-DUP “regime” was “devoid of ideas, incompetent” and “corrupting our fledgling democracy”. If I had my way we would be in opposition by Christmas,” she said.