About �22m was stolen from the bank on 20 December

Mr Robinson said the consequences of mainstream IRA involvement in the raid on the Northern Bank head office in Belfast would be "far reaching".

Police Service Chief Constable Hugh Orde is expected to brief the chair of the Policing Board later this week.

It is thought that he may make his first public comment about the crime.

'Paramilitary activity'

The DUP deputy leader asked whether "political consequences" have so far silenced Mr Orde.

Mr Robinson said: "When this robbery took place, I warned that, if the IRA was involved, it would be a 'lethal blow' to Sinn Fein's position within the process.

"It is time for the chief constable to come clean and tell us what he knows about republican involvement in the Northern Bank raid."

He added: "If the IRA are shown to be involved in this robbery it will illustrate we were right to demand clarity and certainty of the decommissioning of IRA arms and a testing period to gauge whether or not all paramilitary and criminal activity had ended."

Republican sources have said the IRA was not involved.

But this has not stopped the speculation.

Peter Robinson called for Mr Orde to "come clean"

The robbers stole millions from the vaults of the bank's headquarters at Donegall Square West on 20 December, as the families of two bank officials were held hostage.

The families had to spend Christmas away from their houses in Poleglass, near Belfast, and Loughinisland, in County Down, after they were preserved as crime scenes.

The Police Service of Northern Ireland has said the possible involvement of paramilitaries is a "key line of inquiry".

The police have carried out a number of searches in west Belfast.

Meanwhile, it has been confirmed that the Northern Bank will not be able to claim compensation from the government for the raid, even if the chief constable decides it was the work of a terrorist organisation.