The New South Wales Environment Minister has been ridiculed by the Opposition after telling a budget estimates hearing that logging protects koalas.

Robyn Parker was being questioned at the NSW Parliament over the State Government's election commitment to protect threatened species, including koalas.

Labor MP Luke Foley asked Ms Parker how the promise could fit with a decision to allow logging in important koala habitats at Bermagui and in the Boambee State Forest, in the state's south and mid-north coast.

"You might not understand how forestry agreements work. It seems as though you don't," Ms Parker said.

"Because they are agreed. We regulate and that logging protects koalas."

"How does the logging protect koalas? It removes its habitat Minister," Mr Foley said.

The pair continued their heated exchange.

"Your party's election policy, on page one, promised better protection for koalas. You even badged the cover with a photo of a koala," Mr Foley said.

"We stand by our commitments and when it comes to forestry we are about getting the balance and protecting our native species," Ms Parker said.

The Minister and Mr Foley then crossed swords again over the Threatened Species Conservation Act.

"Minister, do you have the foggiest notion what you're talking about?" Mr Foley said.

"What, are you wanting to put it in the Act?" Ms Parker replied.

"It's already in the Act, Minister," Mr Foley said.

Later, Ms Parker said her claim that logging protects koalas was a slip of the tongue.

She has told the Macquarie network she was being badgered.

"[It] doesn't help koalas you know, this was a heated exchange," she said.

"I was interrupted continuously and so I've missed a couple of words out in one sentence."

Ms Parker will have to face another four-hour grilling as the committee wants her back for a supplementary hearing.