It [Bloody Sunday] turned out to be the worst day of all our lives

Martin McGuinness

Mr McGuiness also did not deny a suggestion put to him that he was second in command of the IRA at the time, something that emerged in his signed statement to the inquiry, obtained by the BBC in January.

The MP said: "Everybody knows that every single person shot on that day was an innocent marcher.

"So they now move to plan B and plan B is if you can't blame the people who were killed on the day try to blame Martin McGuinness."

The Saville Inquiry, sitting in the Guildhall in Derry, is examining the events of 30 January 1972 when 13 civilians were shot dead by British soldiers after a civil rights march.

A 14th person died later.

Frank account

In the interview to be broadcast on this, the 30th anniversary weekend of the riots, Mr McGuinness promises to give a full account of his role as a 21-year-old in the civil rights march to the inquiry.

But he also expresses doubt about the inquiry's capabilities.

"There is a sense within many people within the city, that the ability of the Saville Tribunal to achieve the full truth is very limited".

To those who have dubbed the inquiry a costly examination of a single tragedy, he replies he is prepared for a South African-style truth and reconciliation process tackling deaths on all sides.

The Northern Ireland Education Minister says: "It [Bloody Sunday] turned out to be the worst day of all our lives.

"I think in Derry's history it was the blackest day.

"And it's a day that has lived with us over the course of the last 30 years".

United Ireland

Asked if he thinks if he will see a United Ireland in his lifetime, he says that he hopes so.

He says that they might be "well on their way" to this goal by the 100th anniversary of the 1916 Easter Rising in Dublin.

But with regards his role in what he describes as the freedom struggle in Ireland, he concludes: "I haven't done anything that I'm ashamed of."

He continues that he has already said that many wrong things happened and people lost their lives on all sides.

The full interview with Mr McGuinness can be seen on BBC News 24's One to One programme on Saturday at 0645GMT and 2045GMT.

On Sunday it can be seen on BBC News 24 and BBC One at 0730GMT and at 2145GMT on BBC News 24.