First Minister Peter Robinson has said the conviction of republican Thomas "Slab" Murphy for tax evasion was an "important judgment" and said his trial without jury in the Special Criminal Court was entirely appropriate.

He described criticism of the lack of a jury in Murphy’s trial as “sheer madness”.

The Democratic Unionist Party leader said: "The idea you could have a jury trial in such a case is sheer madness.

"I welcome the fact that the conviction has taken place. I will resist any temptation to make reference to Al Capone and the style of his conviction. It is essential to say nobody is above the law and everyone is answerable to the courts."

Sinn Féin leader Gerry Adams had said Mr Murphy was denied his rights by having his trial heard in the non-jury Special Criminal Court.

Mr Robinson said with or without a jury, he believed the decision would not have been any different.

‘A good republican’

Speaking at the launch of a new cross-Border crime taskforce, Deputy First Minister Martin McGuinness said Mr Murphy is a good republican, and that his efforts in the peace process have been invaluable.

He said: "I don't think we can dismiss the contribution people make especially when it is a dangerous occupation to be involved in - building support for the peace process. The work that Tom Murphy done in that area was good work and that makes him a good republican."

Mr McGuinness said Sinn Féin have long called for the abolishment of non-jury courts.

He said the party was united in its view that people have a duty and responsibility to pay their taxes.

However, the Deputy First Minister said many politicians and senior business people have been convicted of similar crimes and have not had the same level of criticism.

Amazing achievement

Mr McGuinness said the peace process is known across the world as an amazing achievement.

He said: “The amazing [achievement] wouldn’t have happened without the work of Tom Murphy. We need to understand that.

“Tom Murphy has found himself before a court on Revenue matters. There have been TDs who have found themselves before court on Revenue matters, there have been business people before court on Revenue matters, but none of them are being described as criminals.”

Minister for Justice Frances Fitzgerald and Minister for Foreign Affairs Charlie Flanagan both insisted the Special Criminal Court was an invaluable part of the justice system.