More than 150 false killer whales have been euthanised after a mass stranding on a remote beach in Tasmania, Australian.

The pod of 157 whales became stranded near Arthur River on Tasmania's northwest coast on Tuesday (Feb 18).

The animals remained beached for over 48 hours before experts made the difficult decision to begin euthanasia operation on Thursday (Feb 20).

Incident Controller Shelley Graham said the challenging location and severe weather conditions left rescuers with no viable options.

She said: "Outcomes like this take both a mental and physical toll."

"I'm really proud of the exceptional effort all members have put in to get the best animal welfare outcome possible."

Dr. Sarah Michael, an expert wildlife veterinarian who oversaw the euthanasia, said it was the only humane course of action.

She said: "I observed the euthanasia operation and I am confident it was accomplished humanely using our established best practice procedure. "

"I'm also confident that euthanasia was the right decision for this complex situation."

Post-mortem investigations have begun with wildlife pathologists carrying out necropsies to determine the whales' health and possible causes of the stranding.

Authorities have confirmed the carcasses will be left to decompose naturally due to the remote and rugged terrain.

Graham said: Not only is this the most natural option, but we are also faced with very limited ability to remove the carcasses."

The Tasmania Parks and Wildlife Service has closed roads and beaches in the area, urging the public to stay away.

Officials have also reminded people that all whales are protected, even after death and that it is illegal to interfere with the remains.

Graham added: "We thank the local community for their hospitality. "

"It's also been incredibly pleasing to see people adhering to site closures and allowing the operations to take place."