An Australian court has found a Japanese whaling company guilty of “wilful contempt” of court for breaching an order to stop killing whales, and has fined it $1m.

On Wednesday, the Australian federal court heard an application by Humane Society International (HSI) as part of a decade-long legal battle against the company Kyodo Senpaku to stop Japan killing whales within Australia’s Antarctic whale sanctuary.

HSI alleged that the company had several times breached a 2008 injunction to stop taking whales in the sanctuary.

It is the first finding of contempt of Australia’s Environment Protection and Biodiversity Conservation Act.

Federal court judge Jayne Jagot found Kyodo had engaged in all the alleged breaches.

“I accept in effect all of the written and oral submissions of the applicant which have been put before me today,” Jagot said.

“It is unnecessary for me to do more than provide a brief outline of the reasons why I am satisfied that the applicant has made out its case to the requisite standard of proof, being beyond reasonable doubt, that Kyodo has committed contempt of court as identified in the statement of charge.”

She said the public interest in the 2008 injunction, the need to deter Kyodo and others, and the fact there was some evidence the company “sought general commercial revenue” from the whaling had all contributed to the penalty.

“I am satisfied that a penalty of not less than $250,000 for each of the four whaling seasons should be imposed on Kyodo,” Jagot said, adding that the breaches were not merely technical, but were intentional and wilful acts.

“I am satisfied beyond a reasonable doubt that the actions of Kyodo fall within the category at least of wilful contempt. That is, there is no possible basis upon which an inference could be drawn that the breaches of the 2008 injunctions were casual, accidental and unintentional,” she said.

“They were wilful actions of Kyodo, done I am satisfied in circumstances where Kyodo had knowledge of the orders and what they required.”

Barrister Jeremy Kirk SC, appearing for HSI, told the court Kyodo committed “serious offences” by flouting the court order and should be fined “at least six figures”.

Kyodo has not appeared in any of the proceedings.

The action was launched following indications that Japan – which does not recognise Australia’s sanctuary – would continue whaling operations in the Antarctic this year.

The HSI’s Australia director, Michael Kennedy, urged the Australian government to put pressure on Japan to comply with the order.

“If whaling in Antarctic waters does resume this year, as we fear it will, and Kyodo continues to ignore the injunction, we ask that the Australian government raises this with the Japanese government to ensure that Australian laws for the protection of whales are observed.”

The executive director of the UK branch of HSI, Claire Bass, said: “The British government committed itself to opposing commercial whaling and now, as we enter high-level negotiations over trade deals and the UN, is the chance to prove it. Blatant defiance of international sanctions against whaling must be a political deal-breaker.”

In 2014, the International Court of Justice ruled that Japan must halt whaling in the Antarctic after finding it was not conducted for scientific purposes.