Australian police have arrested a 17-year-old on terror charges in a Melbourne suburb and say they have halted a plot to detonate three homemade bombs in the city.

A house was raided in the northern suburb of Greenvale on Friday.

Five men were detained last month, also in Melbourne, for allegedly planning an attack on an Anzac Day ceremony.

Last September saw the country's biggest counter-terrorism operation, with 15 people arrested.

The arrested youth has not been named, but is due to appear in court on Monday.

The charges include "preparation for a terrorist act" and possessing "things connected with a terrorist act".

Police detonated three devices found during Friday's raid in Greenvale.

"There is evidence of a bomb plot that was in a reasonably advanced state of preparation," said Prime Minister Tony Abbott on Saturday.

Police said they were unable to confirm what the target for the alleged attack was.

"But let me tell you, something was going to happen," Australian Federal Police (AFP) Deputy Commissioner Mike Phelan told a press conference in Melbourne.

"As a result of Victoria police and AFP interception yesterday, some Victorians are going to be alive," he added.