The IRA practise of ‘disappearing’ people they executed in the 1970s was terrible, shameful and one of the worst things that happened during the Troubles, Martin McGuiness has said.

Northern Ireland's deputy First Minister also said Britain's Queen Elizabeth had a "very genuine commitment" to the Northern Ireland peace process.

In a wide-ranging interview with Marian Finucane this morning, Mr McGuinness said he had voiced his opposition to the IRA practise of “disappearing” people – burying the bodies of people they had executed in such remote places that, they hoped, they would never be found. To him there was “no rationale” for the practise.

The IRA has admitted being involved in the 'disappearing' of nine people during the Troubles in Northern Ireland. The most high profile of these was Jean McConville, a mother-of-ten from west Belfast who was murdered in 1972 and buried on a beach in Co Louth. It was claimed she had been passing information to the British Army in exchange for money though an investigation by the Police Ombudsman for Northern Ireland rejected this claim

Asked why the IRA ’disappeared’ people ather than leaving their bodies - both as a ‘warning’ and to allow their families to have funerals, Mr McGuiness said he believed it was because Republicans in the1970s wanted the public focus to be on the conflict between the IRA and the British and not on how they dealt with informers.

“It was something they didn’t want to be publicly associated with, and that was the public execution of people from their own community who had been in the employ of or who had been agents for the British forces. I don’t accept that argument and I said that at the time.”

He said of the practice: “Terrible. Absolutely terrible and shameful and very, very wrong, in my opinion. It was awful. I suppose in the context of a very bitter conflict where terrible things were happening on all sides, this was one of the worst things that ever happened. “

He was asked about shaking the British monarch’s hand during her visit to Belfast in June 2012. “I made the argument that this was an opportunity to reach out the hand of reconciliation through her to the Unionist community and I believed it would have been a mistake not to meet with someone who obviously herself was making an effort. And so the handshake happened. There was a lot of discussion within the party before it.”

On accepting the invitation to the banquet in Windsor Castle on the occasion of the State visit to Britain by President Higgins, Mr McGuinness said the thing that "rankled most" with Republicans was his wearing a white dress suit.

When he had to stand for God Save The Queen and toast the queen, he said he thought to himself: "'This is a first'.

"To me it was the decent thing to do. I was there, alongside Peter Robinson, to represent the Northern Executive and I wasn't up for a half-baked approach to it. Isn't that what equality is all about? The queen of England knows that she is not my queen and she knows the President of Ireland is my President, but I show due respect to both of them."

He said he had no doubts that the queen was a person “who really, absolutely believes she has a role to play in the process of reconciliation” and she had a “very genuine commitment to the whole process”.

He said of the fragility of the peace process: “I think that things are difficult at the moment, mostly because of the failure to get a comprehensive agreement on the past, parades and the whole issue of flags and identity.”

He said there was a short window of opportunity, now the elections were over, to resume negotiations at the Hass talks, before the marching season began in July