New Zealand Oil & Gas has asked to be placed in a trading halt for around four hours on both the New Zealand and Australian stock exchanges, pending "a material announcement regarding how NZOF progresses with a material asset."
The company is making no further comment.
However, information on the company's website suggests the announcement is likely to be regarding its potential involvement in developing an offshore oil field in Tunisia, known as Cosmos.
In a "latest news" section relating to the Tunisian prospects, NZOG says studies to analyse the various options for developing the Cosmos reservoirs began in February 2012, with "a final investment decision expected to be made in March 2013."
"If the field is developed, first production would be expected to begin in late 2014," NZOG has said.
NZOG paid US$3 million for a 40 per cent stake in the concession, which lies in the Gulf of Hammamet, offshore Tunisia, in partnership with the operator Storm Ventures International, a wholly owned subsidiary of Canadian Chinook Energy (40 per cent) and Tunisia's state-owned oil company, ETAP, which holds 20 per cent.
The concession contains an oil discovery, Cosmos A. Independently proved and probable oil reserves of 9.2 million barrels have been attributed to the Cosmos South block.
"If an oil field development is agreed to by the partners, NZOG will pay the first US$19m of Storm's share of the development costs," the website notice says.
NZOG shares fell 1.1 per cent this morning to 93 cents before the trading halt was announced.