Black Hawks fly in Melbourne sky

Black Hawk helicopters have been spotted flying low over Melbourne's suburbs but don't be alarmed - we're not under attack.

Up to five military choppers in the Australian Defence Force training exercise have been flying in the afternoon and evening since last Thursday.

The ADF warns some flight paths are lower than normal.

"How LOUD was that!!!" Williamstown resident Roxana Ulrich posted online.

"The first one just flew low over my roof, down along the beach and back over the Jawbone Marine Sanctuary."

Residents in St Kilda, Surrey Hills and Camberwell have also reported seeing the military aircraft.

"The training is being conducted to ensure the Australian Defence Force maintains the highest level of capability to respond, where required, to support national interests," a statement reads on the army website.

The training exercise, which ends about 11.30pm each night, will run until Friday.