No sign of tangled whale off NSW coast

There's been no sign of a humpback whale seen tangled in rope off Sydney for more than a day after weather conditions forced search crews to call off their mission.

NSW National Parks and Wildlife Service on Wednesday said finding the sub-adult mammal had been "like trying to find a needle in a haystack" after it was first spotted by a whale-watching boat on Tuesday afternoon.

Crews from that vessel managed for cut some of the ropes off but had to leave before the animal was entirely free due to fading light.

Its last known position was about 4km off Bondi Beach, but there's been no sign of the humpback since, despite an extensive search that included helicopter patrols as far north as the state's Central Coast.

The search was called off on Wednesday after rough conditions made observations virtually impossible.

A NPWS spokesman said a decision on whether to attempt further searches on Thursday would be weather-dependent, however crews remain ready to mobilise quickly in case anyone spots the whale.