Search continues for tangled Sydney whale

Julia Carlisle

Crews have made no official sighting of a humpback whale that was tangled in rope off Sydney's coast as an air and sea search for the mammal continues.

The humpback was spotted by a whale-watching boat on Tuesday, 4km off Bondi Beach, with the crew working to cut some of the rope from the animal but being unable to free it entirely.

A helicopter and a vessel set off at first light on Wednesday to try to find and rescue the whale.

"We have had some unconfirmed sightings that we are investigating and therefore still searching," NSW National Parks and Wildlife Service spokesman Adam Cooke told AAP on Wednesday.

The whale would be on its northbound migration, a NPWS spokesman said earlier.

But if the whale was distressed, it might behave erratically and its location could have changed overnight.

When, and if, the animal is found, a specialised and highly trained whale disentanglement team would cut it free, Mr Cooke said.

"In whale season we can get a few whales caught," he said.

"It does happen on their migration usually from ropes from fishing pods that are left in the ocean from fishing operators."

The sub-adult humpback is believed to be somewhere in waters between Sydney and the state's Central Coast, and likely following a pod of whales heading north.