By Carolyn Quek

Deep inside a labyrinthine complex in Paya Lebar sit two rooms, which together are about the size of four basketball courts.

Built from reinforced concrete and brimming with 300 security cameras, they are among the best-guarded places in Singapore - not surprising considering $1.2 billion will soon be passing through them each day.

These are the new cash-processing rooms of Certis Cisco - one of Singapore's largest private security firms - which handles money from ATMs, banks and more than 3,000 retail outlets.

Yesterday, The Straits Times was given a glimpse inside the rooms, which are about to become an essential cog in the system that keeps bank notes circulating.

Inside are four massive, metallic sorting machines - each about the length of a small truck - that will separatedamaged notes from good ones, helping to ensure ATMs remain filled with money. The new machines are capable of processing 1,800 bills a minute.

Much of this work is now done manually in other rooms within the Certis compound.

Despite the prevalence of credit and debit cards, the amount of cash in circulation continues to grow, from $8.17 billion in 1991 to $17.6 billion in 2006.

Security in the new cash-processing rooms will be almost air-tight.

Employees leaving the room will be patted down in a 17-step search and must wear pocketless suits. The outfits are fastened with a tag and employees have to be unbuttoned by security guards when they leave the room, say for a toilet break.

The rooms - both brightly lit with white walls and flooring - are divided into several areas.

The ATM cash will make its first stop at the preparation area, where it is removed from its cassette, a rectangular plastic box, each of which can hold several thousand notes.

The cash is then moved to the processing area where bills are counted, divided into denominations and scanned to see if they are damaged. Once sorted, the cassettes are replenished and returned to the ATMs.

The need to differentiate the "fitness levels" of notes is important as some banks may prefer to have only crisp notes in their ATMs for example, explains Mr Eric Koh, the general manager of Cisco's cash and valuables security unit.

This article was first published in The Straits Times on September 10, 2008.