An Australian man who counselled his wife to commit suicide was sentenced to 10 years in jail in a landmark decision.

Graham Morant, 69, was found guilty of counselling and aiding his wife Jennifer Morant, 56, in her suicide in 2014, reported the BBC.

The self-styled religious pastor is believed to be the first person internationally to be convicted of counselling suicide, according to ABC News.

Justice Peter Davis ruled that Morant was motivated by the payout from Mrs Morant's life insurance policies, which amounted to A$1.4m (S$1.39m). He was the sole beneficiary of her policies.

Mrs Morant, who had suffered from chronic back pain, depression and anxiety, was found dead in her car alongside a petrol generator, with a note saying "please don't resuscitate me".

Morant had driven her to a hardware store to buy the generator earlier, the jury was told.

According to prosecutors, Morant had told his wife that he planned to use the insurance payout to build a religious commune in the Gold Coast hinterland.

"You took advantage of her vulnerability as a sick and depressed woman," Justice Davis said in the Queensland Supreme Court, reported ABC News.

Morant received a maximum 10-year jail sentence for counselling suicide and a six-year sentence for aiding suicide. Both sentences will be served concurrently, according to the BBC.

He will be eligible to apply for parole on Oct 23, 2023.