The incumbent board, which has controlled the company since his departure in 2013, has criticised his past performance running the company, saying he put the company's ownership of the Elk-Antelope field at risk, while Mulacek has accused the board of wanton value destruction since 2013.
InterOil's board has reiterated its view that Mulacek had no clearly articulated strategy and instead "wasted shareholder money on infeasible projects" that conflicted with the corporation's agreement with the Papua New Guinea government and risked the PRL 15 licence.
"Mulacek's tenure as CEO was marked by litigation that damaged InterOil's reputation and threatened the corporation," the company said in a letter to shareholders.
It claimed Mulacek's partners in the sale of a modular oil refinery to InterOil filed a lawsuit alleging fraud and self-dealing, that could have resulted in material damages that jeopardised InterOil's future, and that Mulacek attempted to put Nikiski into bankruptcy "in bad faith" to benefit himself.
In 2008 the Ontario Securities Commission determined that irregularities in InterOil's administration of certain historical stock options grants were the result of a lack of adequate internal controls.
It also said Mulacek's five director nominees, including himself, would have a potential for a conflict of interest.
It said not only does Mulacek's PIE Holdings own a 20% interest in Australia's Kina Petroleum, which owns leases in PNG including one near the Triceratops discovery, he also has a direct interest in the Raptor, Bobcat, Triceratops and has a carried interest in future exploration wells via his presidency of PNG Drilling Ventures.
It says all of his nominees have ties to Mulacek. David Vance is his representative on the Kina board, George Cammon and Olen Overstreet work at PIE Holdings, and David Lasco is a business associate and co-owner of a company that owns an interest in the PRL15 license, as well as a direct interest in the Raptor, Bobcat and Triceratops discoveries, with no oil and gas experience.
"We believe that Mr Mulacek's attempts to reduce the size of the board and elect a board composed almost entirely of himself and his handpicked nominees is a step in Mr Mulacek's pursuit of a self-serving agenda to take control of InterOil's board and thus InterOil's future," the letter said.
Mulacek, who claims to represent around 7.5% of InterOil shareholders, said the company's share price has declined by about $US60, since he left, and he puts the blame for the substantial destruction of shareholder value at the incumbent board's feet.
Mulacek argues that InterOil has seen tremendous value destruction at the bands of a board that has failed to provide effective oversight, with a flawed managerial and operational structure.
He is critical of the sale of an interest in Elk-Antelope to Total by "allowing management to dispose of assets at fire-sale prices", cost overruns, repeated operational failures and high and increasing debt levels.
He is critical of the compensation levels on offer, and CEO Dr Michael Hession's "golden parachute" payment due in the event of a change in control of the company, which he said is "abusive".
He argues he has tried to engage with the board over the past two years, but said they had failed to be open with shareholders, and in January, as the oil price cratered, he launched his requisition resolution to try to fix the company.
He described his nominees as "all highly qualified and would bring much-needed shareholder-focused representation to the board".
"Each of us would also bring capital allocation and operational expertise, along with deep industry-specific experience, to the board, all of which are currently lacking and desperately required in order to improve the health of the company."