Disgraced businessman and convicted sex offender Ron Brierley has resigned his knighthood.

The 83-year-old pleaded guilty in April to possessing child sex abuse material after being caught by Australian police in 2019.

He is due to be sentenced later in 2021.

The shocking conviction led Jacinda Ardern’s government to repeal his knighthood, awarded in 1988 for “services to business management and the community”.

Ms Ardern said if Mr Brierley hadn’t resigned the knighthood, she would have taken it.

“Had he had not done so it would have been removed,” Ms Ardern said in Wellington on Tuesday.

“I think it’s a sad day for the children of New Zealand and, indeed, the world when someone is found guilty of possessing such horrendous images.”

A statement from the New Zealand Prime Minister’s office said the Queen had been informed of the resignation, and Mr Brierley was no longer able to use the title “Sir”.

Mr Brierley, who has an estimated net worth of $A200 million, has also been asked to return his insignia.

-AAP