Some security experts are warning ASIO would have to employ six times the number of staff to watch all potential terrorism suspects around the clock.

Sources say the intelligence agency would have to add at least 9000 staff at a cost of at least $1 billion a year to watch all suspects.

The man behind Friday’s terror attack on Bourke Street was known to authorities, but they say there was no intelligence to suggest he was planning an attack.

Deakin University counterterrorism expert Professor Greg Barton tells Ben Fordham it’s not worth the extra money.

“The short answer is no because money we spend in one area is money that’s not available to other areas.

“We’ve got to realise we’ve got limited resources and try and get the maximum value from them, and spending that $1 billion would not be good value.”

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