Bank of Ireland technical faults that allowed people to withdraw funds despite having little or no money in their accounts led to officers being sent to some cash machines, gardaí (Irish police) have said.
Large queues formed at many cash machines in the Republic of Ireland on Tuesday after word of the glitch spread.
Posts on social media also appeared to show officers seemingly deployed to cash machines.
The bank said on Wednesday morning that the issues had been resolved and apologised for the disruption.
It warned transfers and withdrawals would still be applied to customers’ accounts.
Gardaí said they had received more than 40 calls from members of the public between 20:00 local time and midnight about an unusual volume of activity at some cash machines across the country.
A handful of calls concerned public order incidents at some cash machines.
One call was made in relation to an assault.
A spokesperson said events involved a “complicated set of circumstances” surrounding large sums of money during a “developing and escalating situation”.
“In response to this dynamic and evolving situation and to ensure public safety, decisions were made locally on a case-by-case basis depending on the circumstances presenting to control rooms and operational members,” they added.