Occidental Petroleum Corporation (Oxy) is in negotiations with Abu Dhabi about its government investment fund, Mubadala, sharing in the US oil company's stake in Iraq's massive Zubair field, a top official said.

"We're going to share part of our share probably with Abu Dhabi and there may be others coming along," chief executive Ray Irani told analysts on a conference call to discuss Occidental's third-quarter earnings.

The precise details of the Zubair consortium have not yet been pinned down, but the head of consortium leader Eni said in an interview with the Financial Times last week that it would require $10 billion in investments.

Irani said Oxy would shoulder somewhere between 25 per cent and 30 per cent of the Zubair costs, and an Occidental spokesman said Mubadala would share part of that if a deal was struck.

South Korea's Kogas is also in the consortium, which won the rights to the Zubair field last week and believes there are 6.6 billion barrels of oil reserves there, compared with current estimates of about 4 billion.

Mubadala is already involved in a joint venture with Oxy and Bahrain to develop Bahrain's Awali field, and Irani said production there would start early next year.-Reuters