SYDNEY -- Tough new antiterrorist laws will soon give troops shoot-to-kill authority when patrolling Australian streets in anticipation of a terrorist attack. But the change will come only after the Australian public has agonized over a claimed loss of civil liberties.

So real does Canberra see a threat from homegrown extremist Islamists that reforms legislated after bitter public debate are set to be put into effect before thousands of overseas athletes arrive in Melbourne for the 2006 Commonwealth Games starting March 15.

The urgent push for far-reaching security powers follows government claims of planned attacks on Melbourne Stock Exchange and Sydney Harbor Bridge. Unnamed cells of Australian-born extremists are also said to have stockpiled explosives and ready-to-use weapons to demolish Sydney's oil refinery and Melbourne's main rail station.