This is the first time his name has been directly connected to an alleged improper demand on Paladin.

The issue of Sir Isaac’s alleged dealings with Paladin was raised by Labor senator Kristina Keneally during her questioning of Home Affairs secretary Michael Pezzullo on Tuesday.

Paladin was controversially awarded more than $500 million in contracts from Home Affairs to assume responsibility for the now defunct offshore processing centre on Manus Island in 2017.

Ms Keneally, the opposition spokeswoman for home affairs, produced an email sent by former Paladin director Ian Stewart to senior Home Affairs official David Nockels which referred to the pair having a telephone discussion about the company’s exposure to corruption risks in November 2017.

Mr Stewart sent Mr Nockels the email after watching Mr Pezzullo give evidence before the Senate’s legal and constitutional affairs committee on April 4 last year during which he denied his department had received notification of any concerns about corruption issues relating to the Paladin contract.

Mr Stewart’s email to Mr Nockels stated that a PNG minister and a senior public servant, who The Sunday Age cannot name for legal reasons, “were unhappy that payments did not come to them either directly or through subcontractors”.

“I also discussed these approaches and previous direct approaches from [another senior PNG official] with you in early November 2017 from my recollection.”

Reading from Mr Stewart’s email and under the protection of parliamentary privilege, Ms Keneally revealed one of the officials who allegedly made direct approaches was “Isaac Lupari”.

Labor has previously sought to question Mr Nockels, a first assistant secretary, over Mr Stewart’s disclosures to him but he has not been made available to appear at recent Senate estimates hearings.

On Tuesday, Mr Pezzullo was resisting Ms Kenneally’s push for Mr Nockels to give evidence on the basis his departmental role had changed some time ago.

But the clerk of the committee advised that Mr Nockels could be called to appear to answer questions about his previous responsibilities.

The committee then held a meeting in private to discuss the clerk’s advice and ruled that Mr Nockels should join Mr Pezzullo to answer questions about Paladin. Mr Nockles had to rush to Parliament House to appear.

Ms Keneally took Mr Nockels to the April 4 email sent to his official government address by Mr Stewart and asked if he remembered a November 2017 phone conversation with Mr Stewart about alleged corruption and bribery in PNG.

Mr Nockels said he could not recall such a discussion. Before Ms Keneally could get another question to Mr Nockels, Mr Pezzullo intervened to say he as the head of the department would take the Labor senator’s entire question on notice and provide a response at a later date.

He acknowledged that Mr Stewart’s email “clearly must be on our systems” and committed to providing the committee with Mr Nockel’s official phone records for 2017 to capture any phone calls from the former Paladin director.

The Sunday Age approached Sir Isaac’s office for comment. He has previously distanced himself from reports of improper demands on Paladin by senior PNG officials.

Sir Isaac last year authorised an advertisement in PNG’s Post Courier newspaper that claimed “fraudsters” had been impersonating senior politicians and officials to seek improper payments from Paladin directors.

Commonwealth Auditor-General Grant Hehir in May reported Home Affairs had “largely” followed procurement rules in its engagement of Paladin and other contractors.

Mr Hehir found the awarding of contracts was “largely” in line with Commonwealth procurement rules and contractors’ performance was “partly adequate”.

But he also noted there were “no performance monitoring or reporting requirements for an average of eight months” while the contractors were operating under letters of intent until contracts were signed.