PSNI chief constable Hugh Orde is likely to be questioned today about the first arrests in connection with last December's £26.5 million robbery of the Northern Bank in Belfast.
Two men in their early 20s were arrested by police at their homes in Kilcoo late on Tuesday night while a third man was arrested in Belfast yesterday afternoon in connection with the robbery. They can be held without charge for 48 hours and thereafter for five further days, if a court extension is granted.
One senior security source described these arrests as "significant" as they marked the first major development in the investigation since the robbery on December 20th last year.
The PSNI has been criticised for failing to make any perceived substantial progress in the investigation into the robbery which Sir Hugh, An Garda Síochána and the British and Irish governments have blamed on the IRA. The IRA has denied involvement.
The chief constable, who is meeting the policing board today, has on a number of occasions insisted that the investigation would take a long time to complete. The fact that police have made their first arrests after 10 months indicated that "significant" progress was now being made, the security source said.
The two men arrested in Kilcoo are not members of Sinn Féin but come from known republican families, said south Down Sinn Féin Assembly member Willie Clarke yesterday.
Last night the PSNI disclosed that a third man (30) was arrested in Belfast yesterday.
"This is a political stunt, this is political policing, these young men are totally innocent," said Mr Clarke.
The stepfather of one of the Kilcoo men said his stepson laughed in disbelief when police told him he was being arrested in connection with the Northern Bank robbery.
Kilcoo is a small mainly republican village about 12 miles from Loughinisland in Co Down where a bank official's wife was held hostage by elements of the robbery gang. Police refused to say if there was any link between the hostage-taking and the arrests.
One of the men runs a contracting firm and the other works with him, said Mr Clarke. He accused police of being heavy-handed during the arrest, which took place shortly after the men returned on Tuesday night from working in Dundalk.
Yesterday police carried out a number of searches and seizures which were centred on the home of the contractor. They seized items such as mobile phones, a computer, computer disk, credit cards, cash, passports, and other documents, said his family.
Sir Hugh is likely to be questioned by the media about the development when he attends the policing board meeting this afternoon. He normally holds press conferences after such meetings, although he may say that for investigative reasons he is limited in what he can reveal about the state of the robbery inquiry.
Board questions to the chief constable are tabled in advance but board members today may also try to elicit information from him on the investigation.
Last month Garda Commissioner Noel Conroy said money recovered during an investigation into a suspected IRA money-laundering operation was part of the Northern Bank haul. Gardaí recovered about £2.5 million during this operation in Cork and believe they have accounted for a further £2.5 million that was partially destroyed.
While the rest of the £26.5 million remains unaccounted for Sir Hugh has said this was "largely irrelevant" as he believed the robbers were not in a position to use the money. Last March the Northern Bank replaced its £10, £20, £50 and £100 notes with new notes carrying a different logo to render the stolen notes useless.