Webber cites dissatisfaction as the main reason for his departure.

“I’ve been involved both here and overseas on a variety of assignments, most of which I have thoroughly enjoyed, for over 30 years,” Webber told PetroleumNews.net.

“I just haven’t enjoyed my time at Austral as much; it’s hard to say why exactly.”

Meanwhile Austral Pacific chairman David Newman said on Friday that in Webber’s time at the company “significant opportunities”, such as Cardiff and the Kahili fields, had remained undeveloped, and the company would be reviewing its leadership structure.

However, Newman did note milestones such the restarting of production from the Cheal oil field using temporary facilities, the initiation of the full field development of Cheal, the acquisition of Arrowhead Energy and the Douglas gas and condensate discovery in Papua New Guinea.

Born and bred in New Zealand’s petroleum capital, New Plymouth, Webber had high hopes when he started at Austral. He told PNN at the time that he wanted to make Austral one of Australasia’s best independents.

Before joining Austral, Webber was New Zealand general manager for Fletcher Challenge Energy in the late 1990s and early this decade.

Prior to that, he spent several years with BP on several different assignments. He worked in New Zealand on the Maui and Kapuni fields, and later, on downstream activities; in Britain on the commercialisation of some North Sea fields; and in Melbourne working on PNG’s Hides gas and Kutubu oil field developments.

Now he is uncertain what lies ahead.

“I don’t yet know what I will do next, perhaps stay in New Zealand, either Wellington or New Plymouth, or maybe go overseas,” he said.

Newman said he and fellow Austral Pacific director Peter Hill would jointly assume the chief executive’s duties and conduct a review of the organisation to determine and improved and permanent leadership structure.

He also said he did not expect any trouble finding a replacement for Webber, as there had been some other strong contenders at the time Webber had applied for the chief executive's position.

A replacement would be chosen once plans to recapitalise Austral had been finalised, according to Newman. The company was considering raising several tens of millions of dollars from existing and perhaps new shareholders within the next three months.

Austral Pacific's board was still committed to the expansion strategy articulated by Webber last year, he said. Austral last year took over Arrowhead Energy and could undertake further mergers and acquisitions.

There had been speculation last year of a possible merger between Austral and fellow New Zealand explorer TAG Oil – both started by Canadian investor Alex Guidi – but today TAG president Drew Cadenhead said this would not happen.

“There are no plans to merge the companies at this present stage,” Cadenhead told PNN.

"We looked at it, there were some synergies between the companies, but the business plans were quite different and we decided not to proceed."