The prime minister, Malcolm Turnbull, is being pressed by Labor and the Greens to explain what was said in a private meeting that led to the awarding of a $443.8m grant to a small not-for-profit group for the Great Barrier Reef without a tender process.

It comes after new revelations that the environment and energy department secretary, Finn Pratt, was not present at an April meeting between Turnbull, the environment and energy minister, Josh Frydenberg, and the Great Barrier Reef Foundation chairman, John Schubert.

The Greens senator Peter Whish-Wilson, who is chairman of a Senate inquiry examining the process behind the grant, said he had never heard of a prime minister making an unsolicited grant offer of more than $400m to a small foundation before.

“If he won’t come clean, I am going to ask the committee to support my suggestion as chair of this inquiry to call the prime minister and the environment minister to answer questions at the next hearing,” he said.

“If the prime minister and environment minister ignore that request, then there are other options the Senate can pursue to get them to answer questions.”

Committees can invite members of the House of Representatives to appear at Senate inquiry hearings and, under Senate standing orders, senators can also pass a motion inviting them to give evidence. But they cannot compel them to attend.

The Labor senator Kristina Keneally said that, based on evidence put to the inquiry, so far she was concerned there might be no official record of what was said at the meeting that resulted in the almost $500m budget allocation to the foundation.

“From the evidence we have to date – and mind you, we haven’t heard from anyone who was actually in the private meeting between Malcolm Turnbull, Josh Frydenberg and Dr John Schubert – it seems there was no public servant in the room. That worries me,” she said.

“First of all, it could mean that there is no official record of the meeting. Secondly, it suggests Malcolm Turnbull went into that meeting without proper advice.

“What advice did Malcolm Turnbull receive from Treasury about the financial risks of giving away $444m of public funds in one go to a small, private foundation? What did the Department of the Environment tell him about the risks of handing responsibility for the reef’s future to one tiny private charity? Or did he have any advice at all?”



Labor’s environment spokesman, Tony Burke, said the grant was for almost $500m of taxpayers’ money but “there’s no process, no policy and no probity”.



“All roads lead back to Mr Turnbull,” he said. “The future of the reef shouldn’t be determined by the miners and the banks. We won’t be letting this go.”

The foundation has also confirmed the identities of its original founders and directors, which it had previously not disclosed.

In a statement on Wednesday, the foundation said the idea was conceived by Sir Sydney Schubert, who was a senior public servant under the Bjelke-Petersen government in Queensland and a founding director of the Great Barrier Reef Marine Park Authority.

The current chairman, John Schubert – no relation to Sydney – John Boyd Reid, who was the last of his family to chair James Hardie, one of Australia’s biggest asbestos producers, and Sir Ian McFarlane, who sought to develop shale oil in Queensland, were also at an initial meeting in 1999 when formation of the charity was discussed.

The foundation issued the statement following questions from Guardian Australia about the foundation’s Asic records, which name its founding four directors as Sydney Schubert, Reid, McFarlane and David Windsor, who was an executive director of the Association of Marine Park Tourism Operators.

The foundation was registered as a company in 1999.

“It is our understanding that Sir Sydney Schubert’s idea for forming the foundation was to create a charity to bring science and business together with a common purpose of protecting the Great Barrier Reef,” a foundation spokesperson said.

Keneally said the foundation should have been upfront with the parliament when asked about its founding members.

The foundation had previously said its establishment came after a chance meeting between businessmen at an airport but its website now references Sydney Schubert’s involvement.

“For 20 years the Great Barrier Reef Foundation has kept the identity of their founders a secret from the public,” Keneally said.

Guardian Australia has contacted the prime minister’s office repeatedly this week with questions about the Great Barrier Reef Foundation and has received no response.