Returned fighters shouldn't roam streets

Prime Minister Tony Abbott says returned Australian jihadis are a menace to the country and shouldn't be "roaming the streets".

Responding to reports up to a dozen Australians want to return home after fighting with extremist groups like Islamic State, Mr Abbott reaffirmed his intention to lock them up.

However, the prime minister told reporters in Brisbane there are provisions that could mitigate the severity of criminal sentences if they cooperate with authorities and enter guilty pleas.