A board director for the Great Barrier Reef Marine Park Authority has been accused of a potential conflict of interest over public funding directed to companies working on crown-of-thorns starfish culling.

Margie McKenzie sits on the board of the authority and also owns a company called Gempearl with her husband, Col McKenzie.

More than $20m in taxpayer funds was spent by the reef authority on killing crown-of-thorns starfish, which preys on coral.

According to reports by the ABC, the money was directed to two not-for-profit companies that then subcontracted the culling work to Gempearl.

Col McKenzie is also linked to the two companies that subcontracted the work – the Reef and Rainforest Research Centre, on which he serves as a board member, and the Association of Marine Park Tourism Operators, as its executive director and company secretary.

Freedom-of-information documents show Margie McKenzie failed to declare her interest in Gempearl for her first two years on Great Barrier Reef Marine Park Authority’s board.

She made a clarification to her declaration of interests in 2015 that listed her role as managing director of Gempearl.

Guardian Australia has contacted the McKenzies for comment.

Margie McKenzie told ABC she had left the room during any Great Barrier Reef Marine Park Authority discussions about crown-of-thorns starfish.

On Tuesday morning, the environment minister, Melissa Price, said she was investigating.

“Given the talk overnight, in the media in particular, clearly we’re investigating this,” she said. “Because I do take the issue of conflicts of interest very seriously, so we are investigating that matter today.”

Labor’s environment spokesman Tony Burke, said “one of the consequences of having a skills-based board of people who are actively involved in the Great Barrier Reef is there will be occasions where different board members will have conflicts of interest.

“It’s essential that all the probity rules are followed whenever this arises.”

The environmental organisation the Australian Conservation Foundation said it was “increasingly concerned about how the Great Barrier Reef is being managed”.

“The conflict-of-interest questions around the allocation of taxpayer funds administered by GBRMPA will worry everyone who loves our reef,” the foundation’s chief executive, Kelly O’Shanassy, said.

“Australians should be able to be confident the Great Barrier Reef is being properly looked after and the authority and other relevant bodies are making the best decisions for its future, not the narrow interests of some.”

Price said her department and the Great Barrier Reef Marine Park Authority would be examining the adequacy of the authority’s processes for managing conflicts of interest.