Britain is blocking reconciliation on the island of Ireland by refusing to face up to its role in the violence of the Troubles, Martin McGuinness said at Westminster tonight.
The senior Sinn Fein figure addressed an audience in Portcullis House at the Houses of Parliament in London after his historic handshake with the Queen in Belfast.
But while he hailed that moment as a vital step in healing relations between Protestants and Catholics, he said efforts to broaden the process of reconciliation were being hampered by the British government.
Mr McGuinness, a former IRA commander and now deputy First Minister in Northern Ireland, said Prime Minister David Cameron had failed to involve himself fully in the efforts to build on the peace process, and accused his government of making "a series of very wrong and unhelpful decisions".
The leading republican said: "I genuinely regret every single life that was lost during that conflict and today I want every family who lost a loved one to know that your pain is not being ignored and I am willing to work with others to finding a way to deal with our past so that we can complete our journey to true reconciliation."
He added: "National reconciliation will be built on the firm foundation of mutual respect and decisive actions. That is the context within which I met Queen Elizabeth this week.
"It was in a very pointed, deliberate and symbolic way of offering the hand of friendship to unionists through the person of Queen Elizabeth for which many unionists have a deep affinity. It is an offer I hope many will accept in the same spirit it was offered. Unfortunately, to date, the British State has refused to even acknowledge its role as a combatant in the conflict. That position is no longer tenable as we move forward.
"It is insulting to victims of events like Bloody Sunday in my own city when 14 people were killed and it is insulting to people's intelligence. It is also excluding the British state from assisting a genuine process of national reconciliation in Ireland. A process which, though embryonic, is nevertheless under way. There are issues that have not been brought to a conclusion, specifically the issue of the legacy of the conflict. The British Government has a big role to play in that."
Mr McGuinness said that he and his unionist partner in the Stormont power-sharing administration, First Minister Peter Robinson, had met US President Barack Obama more times than they have met Mr Cameron.
The Sinn Fein figure accused the government of "very wrong and unhelpful decisions" including the imprisoning of high-profile republicans who had been released on licence, and the failure to fulfil a commitment to hold a public inquiry into the state role in the murder of Belfast solicitor Pat Finucane. He also condemned the refusal to grant an independent probe into the deaths of 11 civilians in Belfast - including a mother of eight and a Catholic priest - who were shot dead by members of the Parachute Regiment in what has become known as the Ballymurphy Massacre in 1971.