Detectives investigating 11 armed robberies across the North West and the Midlands have arrested two men.
Officers from eight police forces have been involved in Operation Robust.
On Thursday, police arrested a 29-year-old man in Merseyside and a 40-year-old man in Milton Keynes.
Both were due to be questioned in Staffordshire, where the operation has been co-ordinated.
The first of the 11 bank robberies under investigation was at the Stockport branch of the HSBC in Greater Manchester on 23 December 2002.
The last was committed on Monday at Kineton in Warwickshire.
The other bank robberies under investigation include three in Staffordshire, three in Lancashire, two in Cheshire and one in West Mercia.