A statement from Basslink on Thursday said the arbitrator had found in favour of Tasmania and Hydro Tasmania and awarded damages of $38.5 million to be paid by Basslink.

Hydro Tasmania is a government-owned body and is Australia’s largest generator of clean, renewable energy.

The disputes in question are over an outage of the Basslink interconnector in 2015. The outage was not fixed for six months.

On 20 December 2017, Hydro Tasmania said it had identified the cause of the Basslink failure and cited two experts, from international engineering consultancy DNV GL which is recognised as a global leader in the field, who said it was because Basslink had exceeded its design limit.

But two days later, Basslink chief executive Malcolm Eccles dismissed the findings, saying that the expert reports cited as proof merely outlined one possible cause of the outage.

In December 2018, Basslink issued a statement saying: "Basslink has consistently maintained its position that the cable failure was a force majeure event under the Basslink Services Agreement and Basslink Operations Agreement. The recent CCI Report further supports Basslink’s view that the cable failure was a force majeure event under the BSA and BOA."

CCI is Cable Consulting International, a UK-based firm regarded as a leading submarine power cable expert, which was initially asked to conduct an inquiry into the cable failure.

On Thursday, the Basslink statement said its claim for for unpaid fees of $31 million against Hydro Tasmania, relating to the period of the outage, was not recoverable, adding that disputes over the Asset Management Plan and the Marine Disaster Recovery Plan had been separately settled.

Eccles said the organisation would take time to review the rulings and determine the next steps. “We are obviously extremely disappointed with the outcomes,” he said.

“We will need some time to review the decisions and consider the implications. In the meantime, Basslink continues to operate efficiently and reliably, connecting Tasmania to the national electricity market.”

Contacted for its take on the arbitrator's decision, a Hydro Tasmania spokeswoman said the details of the award were under consideration and it was not appropriate to comment at this stage.