CANBERRA (XINHUA) - A committee investigating a controversial funding grant awarded by the Australian government will compel the former Prime Minister Malcolm Turnbull to give evidence if needed.

The Australian Senate's environment and communications committee is scrutinising the decision by Mr Turnbull and former Minister for the Environment Josh Frydenberg to award the Great Barrier Reef Foundation (GBRF) A$444 million (S$444 million).

The funding became a contentious issue in Mr Turnbull's final weeks as prime minister after it was revealed that the GBRF, which employed only six full-time staff before receiving the grant, did not apply for the funding, which was the largest grant ever given to an Australian nonprofit organisation.

Peter Whish-Wilson, a Greens senator and chairman of the committee, said Mr Turnbull would be required to offer proof on an private meeting in April with Frydenberg and Josh Schubert, chairman of the GBRF, where the charity was offered the money.

A sitting member of parliament cannot be forced to appear before the committee, but the former prime minister can be compelled to do so when he resigns from parliament on Friday (Aug 31).

"I'll be seeking to work with the committee to invite him as a witness and compel him if we have to," Mr Whish-Wilson told News Corp Australia on Tuesday night.

"I want to know exactly what was discussed, and where did the idea start. It didn't just materialise. Someone has come up with the idea and driven it at the highest level."

Questions about the decision were amplified earlier in August when Michael Myer, a foundational board member of the organisation, described it as "shocking and almost mind-blowing."

Mr Schubert and fellow board members Stephen Fitzgerald, Paul Greenfield and Grant King have agreed to give evidence to the committee on Sept 18.