Detectives investigating the £26.5m Northern Bank robbery have arrested a 35-year-old Belfast man, police have said.
Millions were taken from the bank's vaults last December
The money was taken from the bank's Belfast headquarters last December, in a robbery blamed on the IRA.
Meanwhile, a move to release a bank employee being questioned about the raid failed at the High Court.
Chris Ward was arrested on 29 November, and on Monday a court gave police another 48 hours to question him.
The application to release Mr Ward, 24, was based on the fact that he and his solicitor were excluded from part of the hearing.
Mr Justice Harte upheld the ruling that gave police more time to question him.
The judge at Monday's hearing, Mr Justice Gibson, asked for more detail about the areas of questioning the police wanted to pursue with Mr Ward.
A detective told the judge that the details were pertinent to the police strategy in interviewing Mr Ward - so it was given without Mr Ward or his solicitor present.
Mr Justice Hart said Judge Gibson had used his discretion properly, and threw out the application to have Mr Ward released.
After the hearing Mr Ward's solicitor, Niall Murphy, said his client has stressed his innocence.
"He continues to protest his innocence in Antrim police station where he has been held for a week and if police apply for any further extensions they will be strenuously opposed," he said.
He has now been questioned for longer than anyone else in Northern Ireland since the law was changed last year allowing the police up to 14 days of questioning.
The extension was the third detectives have been given to question Mr Ward, an employee of the bank which was robbed in December last year.
After the robbery, Mr Ward described on television how he was held captive in the run-up to it.
Of the 11 people questioned to date in connection with the raid, three have appeared in court.
Some money seized in County Cork last February was linked to the robbery, but virtually all of the missing millions remain unrecovered.
Police on both sides of the Irish border subsequently blamed the IRA for the raid.