Usually twice a week about 11am, journalists with some of the world's biggest news agencies file into a tiny room at the Australian Bureau of Statistics building on Market Street in Sydney's centre.

The reporters are asked to check in their mobile phones, laptops or any other devices that could conceivably transmit to the outside world. Each is allocated a chair, a desk and a fixed phone, and the blind covering the small window is kept down.

As the minutes tick by, the reporters - from agencies such as Bloomberg, Dow Jones and Reuters - are allowed to call their news editors. But after a line is opened, no further talking is allowed. At 11.25am Telstra's talking clock is switched on, broadcasting the exact time to the room.

With one minute to go, ABS officials walk in, and stand behind the reporters. And as the clock counts down to the third stroke to hit precisely 11.30am, a document containing the day's statistical release is placed on the desk in front of each reporter. For a frantic minute they yell out the numbers back to their editors: ''Unemployment: five-point-nine. Up zero-point-three. Part rate six-four-point-seven.''

These figures are then flashed across screens from Sydney to Wall Street. At 11.30am the statistics are also uploaded to the ABS website where anyone can access them. Before then the figures are treated as confidential and only authorised ABS officials have access, with only certain ABS staff able to access certain figures.

As the data becomes more sensitive, the ABS has become increasingly tighter in its controls. The penalties for the journalists that stray from the rules can range from being banned from the release room to even criminal charges if the breach is significant.

The focus of financial markets is usually what are known as the main economic indicators - such as figures tracking the balance of payments, unemployment, inflation, housing finance and the quarterly national accounts, which contain the all-important GDP numbers. Hundreds of millions of dollars worth of currency trades around the world can hang on a single number.

''[The statistics] give us a gauge of how fast or slow the economy is travelling which impact currency and bond markets. They can also show which bits of the economy are stronger or weaker,'' St George Bank chief economist Besa Deda says.

The ABS is now reviewing its procedures following the arrest of its staffer Christopher Hill for leaking what the bureau described as ''sensitive, embargoed statistics''.