Prime Minister Scott Morrison has taken responsibility for the coalition's controversial $444 million grant to the Great Barrier Reef Foundation.

Responding to months of scrutiny over the payment, which did not go through a tender process, Mr Morrison said as treasurer he wanted the most effective way to make a "significant and urgent" commitment to the reef.

"It made financial sense to consider doing this investment in one instalment, if it were also able to achieve the environmental objectives for the reef," he told The Australian on Monday.