Malcolm Turnbull has been offered his pick of time and place to front a Senate inquiry into a controversial $444 million grant given to the Great Barrier Reef Foundation.
While the former prime minister is not obliged to attend, Labor Senator Kristina Keneally wants him to appear for questioning.
Last week, the committee was handed a fourth extension to deliver its final report by February 13.
Mr Turnbull is believed to be final witness the committee wants to interview before reporting back.
"We've offered Mr Turnbull to name any dates or locations that suit him," Senator Keneally tweeted on Sunday.
He did respond to questions from Greens Senator Peter Whish-Wilson in writing while he was still holidaying in the United States after quitting politics.
In his response, Mr Turnbull was unable to give a firm answer about why the foundation was singled out for the grant.
"As to why the GBRF was recommended by the Department of the Environment and Energy (as opposed to another organisation) you should inquire of the department," he wrote.
