IT was a $22 million encrypted radio system meant to keep police business secret from unwanted eavesdroppers.

But hi-tech hackers cracked the system within 12 months, selling off the technology to tow-truck drivers for up to $25,000 a time. In the past weeks police have changed the code after discovering the radios were also in the hands of criminals, particularly bikies.

NSW police implemented the system three years ago for security reasons.

But within a year tow truck operators were paying $12,000 to have "exclusive rights" to radios encrypted for their area and promised competitors would not have access to the same channel. For $25,000 the entire encrypted system could be bought, enabling the purchaser to listen in on all police channels throughout the metropolitan area.

It is believed more than a dozen tow truck drivers have been listening to the police network throughout Sydney for at least two years and in some cases longer.

NSW police are refusing to even acknowledge there has been any security breakdown with its radio network, which is severely embarrassing to the force. Police were confident the system was foolproof.

It's understood no one has been charged and police still have very little idea how the encrypted codes became so freely available.

Country and regional areas have not been encrypted because of the prohibitive cost.

When asked about the fact the system had been compromised and whether any one had been charged, police refused to answer.

"The NSW Police Force employs a range of strategies to ensure the security and integrity of its communications," said Assistant Commissioner Peter Barrie, who is in charge of the police communications branch. "Those strategies and their effectiveness are regularly reviewed."

A tow-truck driver who had been in possession of a radio for more than two years said yesterday: "The cops have fixed the problem for now. Everyone says their radios have gone dead."

One person recently paid $23,000 to have access to all channels. It was only after word leaked that bikies, and not just towies had been able to acquire the radios, that police acted.

Originally published as Crims bust police code