Great Barrier Reef Foundation chairman John Schubert said he had no idea former prime minister Malcolm Turnbull would offer a $443.3 million grant to his charity, the largest in the history of protecting the national wonder, before a meeting in Sydney in April.

While new Environment Minister Melissa Price on Tuesday backed the controversial grant by the former Turnbull government, Labor has committed to scrapping the grant and asking for the charity to return the money to Commonwealth if it wins office at the next federal election due early next year.