Rescuers in Australia say at least a third of 270 whales stranded off Tasmania have died and more are feared to be dying.

However, crews were able to save 25 of the animals on Tuesday and are aiming to escort more back into the sea.

The Pilot Whales were discovered in shallow waters off the west coast of the island on Monday.

It’s unknown what drew the whales to the shore.

Marine biologists say the rescue mission will likely take days.

Whale beaching’s are common in the region, but one of this size has not been seen in over a decade.

Tasmania last recorded a mass stranding in 2009 involving around 200 whales.

Rescuers from the Tasmanian Marine Conservation Program arrived late on Monday and found 3 groups of whales across Macquarie Heads – a remote tip of the island with limited vessel and road access.

About 200 of the mammals had washed up on a sandbar near a boat ramp, while 30 others were found several hundred meters away.

Another 30 were found further inland along Ocean Beach.