Police are probing a sophisticated multimillion-dollar robbery at Scotiabank's Portmore branch in St Catherine after thieves allegedly used security access codes to enter the bank's automated banking machine (ABM) servicing room and steal an undetermined sum of cash.

The break-in was discovered on Sunday morning when a security guard conducting routine patrols found the door to the ABM servicing room open and alerted bank officials.

Investigators believe the thieves entered the bank compound sometime between Saturday afternoon and Sunday morning.