Counter-terrorism police have launched raids in homes across several suburbs in the Australian city of Melbourne where a suspected terrorist was shot dead last week.

A joint state and federal police operation supported by surveillance helicopters executed search warrants in the suburbs of Seabrook, Kealba, Meadow Heights, Broadmeadows and Flemington, Australian federal police and Victoria state police said in a statement.

The Australian Broadcasting Corporation reported a man had been handcuffed and taken into custody. Police would not immediately confirm any arrests.

Officers said the raids in Australia's second largest city were not a response to a threat to public safety, nor were they related to last week's shooting.

Numan Haider, 18, was killed last Tuesday after he stabbed two police officers during a routine meeting outside a Melbourne police station. Both officers are recovering.

Australian prime minister Tony Abbott said the knife attack was inspired by the Islamic State group.

Two weeks ago, police detained 16 people in counter-terrorism raids in Sydney and charged one with conspiring with an Islamic State leader in Syria to behead a random person.

Small-scale raids continued in that city for days afterwards in what police described as an ongoing investigation.

Earlier this month, Australia raised its terror warning to the second-highest level, citing the domestic threat posed by Islamic State supporters.