Prime Minister Scott Morrison has taken responsibility for a $444 million Great Barrier Reef grant.

The $443.8 million grant to the Great Barrier Reef Foundation has been criticised for being awarded with very little consultation, no tender process, no solicitation by the foundation, and no clear plan for how it would be used.

Questions have also been asked about the appropriateness of the strong links between the Great Barrier Reef Foundation and major polluters.

Prime Minister Scott Morrison says he and the finance minister, Mathias Cormann, as the Coalition’s economic team before the 2018 budget, worked out “the best way to do [the grant] financially”.

“We knew that the position in 2017-18 – Mathias Cormann and I – had improved and that gave us the opportunity to actually make the biggest investment in the future of the reef in one go,” he said.

“Now, had we not taken that decision, I think it would have been a lot more difficult to do that over a number of years.”

Mr Morrison said it was “the right financial decision”.

The $444 million grant was given in a single lump sum, but is to be spent over six years.

The Opposition says the one-off transfer will cost taxpayers millions in public debt interest every year, as the grant money sits in the foundation’s bank accounts.

Labor has threatened to claw the money back if it wins the next federal election.