Large mirrors hang on all the walls of this workplace - not for any aesthetic reason, but as a conspicuous deterrence against thievery.

Here, employees must bring along their passports to work, not because they will be getting on the road, but to prevent them from fleeing the country with any loot.

As added precaution, workers wear pocketless jumpsuits with locks at the collar which can be opened only by the security guards.

To top it all, everyone has an 18-step body search before leaving the workplace, just to make sure no money leaves with them.

With its latest cash-processing centre, which opened officially in Commonwealth yesterday, Certis Cisco Secure Logistics is taking no chances. Seven days a week, 24 hours a day, the centre counts, sorts and accounts for a sizeable proportion of the money that keeps Singapore's cash ecosystem up and running. Cash collected from hundreds of bank outlets, ATMs and retailers arrives here to be processed by high-speed sorting machines and is sent back out to be recirculated for use in the economy.

Across the board, other cash-processing service providers like Aetos Holdings also deploy watertight security measures and monitoring services in their operations.

As of now, Certis Cisco is the only cash-processing provider with a full "hot" backup site, Certis Group chairman Olivier Lim said at the opening. Its Commonwealth centre and the current facility in Paya Lebar will be backups for each other in the event one is down.

Mr Sim S. Lim, DBS' group executive and Singapore country head, whose bank chairs the Association of Banks in Singapore, welcomed the first cash-processing centre certified under guidelines of the Outsourced Service Provider's Audit Report, a set of standards introduced by the association.

"Being certified sets the standards for outsourcing requirements for dealing with cash. This ensures that accuracy and integrity is 100 per cent. In this line, even 99 per cent is not enough," he added.

Aside from counting and sorting, the two cash-processing machines in Commonwealth and two in Paya Lebar single out unfit notes that have been written on, torn or discoloured. These notes are returned to the central bank, and fit notes are withdrawn and returned to the cash cycle.

With close to $1 billion passing through both cash-processing centres every day, security and reliability are key to operations.

To work at the centre, employees undergo thorough background checks and are screened for their financial and criminal records.

Even while the cash is on the go, Certis Cisco pays close attention to its fleet of 114 security vehicles and 330 auxiliary police officers taking the money to and from bank outlets, ATMs and retailers.

The stringent checks and measures are necessities that Ms Salha Mohd Yasin, 50, a trainer at the cash-processing centre, takes in her stride. "We play an important part in the cash ecosystem, especially during Chinese New Year, when demand for new notes goes up," said Ms Salha.

Correction note: The story has been updated for clarity.