Victorian Greens leader Greg Barber has called for greater transparency regarding former ministers and their work in the corporate world. The call came after an article in The Age this week raised the issue of a potential conflict of interest regarding former Labor Minister of Energy and Resources Theo Theophanous, and his current role as a political advisor to energy company Lakes Oil.

During his term as minister between 2002 and 2006, Mr Theophanous played a key role in the creation of the 2005 Geothermal Energy Act and advocated that Victoria should abolish its onshore gas moratorium.

Although The Age did not allege that the former minister was engaging in any illegal activity, the newspaper raised speculation over recent meetings Mr Theophanous has had with state Premier Daniel Andrews and Treasurer Tim Pallas.

The premier and Mr Theophanous were spotted talking at the A-League Grand Final, and a day later he was seen speaking with Mr Pallas – shortly after the treasurer had given a conference speech about Victoria’s plans to hold an inquiry into onshore oil and gas.

When questioned by The Age Mr Theophanous declined to comment on his role or the private talks he had with the politicians. The premier’s office and Mr Pallas’ spokesperson also declined to comment on the nature of the conversations with the former minister.

“The treasurer meets with a range of stakeholders across a number of issues, but does not disclose the contents of those private discussions,” Mr Pallas’ spokesperson told The Age.

Lakes Oil executive chairman Rob Annells said that there was nothing controversial regarding the former minister’s involvement with the company, citing previous high-profile members of the Lakes Oil board.

“We had Alexander Downer on our board … he was an excellent director, and although Theo is not a director, so far we are communicating very, very well and he is a very intelligent man and he has a lot of experience which we are drawing on,” said Mr Annells.

Former federal resources minister Martin Ferguson is of a similar mind and currently serves as a director of gas producer BG Group.

“I actually think former politicians can bring to business an understanding of the workings of government, and a broader understanding of the expectations of the community,” he said.

“Just as [former Greens leader] Bob Brown has devoted his energies to the endeavours of the Sea Shepherd since leaving the senate, it is no different for a former state or federal minister to also work in the business sector, be it of a paid or voluntary nature.”

Mr Barber told The Age that “ministers should be banned for life for representing a company on a particular matter or transaction that they oversaw at the time of being minister”.