A 25-year-old Salford man has been arrested on suspicion of robbery in connection with the raid on Lloyds TSB, Darwen, on June 5.
Two men in balaclavas and armed with machetes and a crowbar forced staff in the bank to hand over cash boxes and bags containing a "substantial" amount of money.
The pair fled in a grey Audi A3 car waiting outside the bank in Duckworth Street with a third accomplice in the driver's seat.
Police said the Audi was found abandoned off Robin Bank Road.
It is thought the raiders got into a second vehicle and left the area.
The arrested man has been released on bail until August.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article