U.S. explorer Anadarko Petroleum Corp has raised its estimate of the amount of natural gas it has discovered offshore Mozambique by two thirds, lifting hopes that East Africa could become a major gas exporter.

Anadarko said on Wednesday it believed its fields in the deepwater Rovuma Basin contained recoverable reserves of at least 10 trillion cubic feet, enough to meet an entire year's consumption by France, Germany, the UK and Italy.

It had previously estimated that the fields, in an exploration block known as Offshore Area 1, located close to the border with Tanzania, contained at least 6 Tcf.

The increase has prompted Anadarko and its junior partners -- a unit of Japan's Mitsui & Co Ltd and Dublin-based Cove Energy Plc -- to double the size of the planned facilities they aim to build to extract and freeze the gas and export it in tankers as liquefied natural gas (LNG).

Our successful drilling program offshore Mozambique continues to expand the already world-class resource potential of this frontier basin, said Bob Daniels, Anadarko senior vice president, worldwide exploration.

Cove Energy Chief Executive John Craven said he was confident of additional discoveries in the area, and analysts at Citigroup predicted reserves of 12 Tcf.

Anadarko's shares traded up 3.3 percent at $63.59 at 1632 GMT, while Cove's London-listed shares closed up 10.9 percent at 68.75p.

Anadarko now plans to bring a second drilling ship to the area to accelerate work. The partners are still targeting a final decision on whether to proceed with the LNG plan in the third quarter of 2013.

The two planned 5 million tonne per annum LNG production plants, known as trains, would cost billions to build, prompting analysts at Citigroup to predict that Cove, which has a market capitalisation of only $550 million, could seek to sell all or part of its interest in the block.

NEW PROVINCE

Oil and gas companies have flocked to East Africa in recent years, spurred by high oil prices, advances in deepwater drilling and difficulties in securing access to reserves in areas historically seen as more prospective, such as the Middle East.

Drilling is progressing in Tanzania, Madagascar and Kenya, and explorers expect more big gas finds.

If it gets to where we think it's going to go, there will be LNG plants in at least two positions along the coastline, said Andrew Lodge, exploration director at Premier Oil Plc, which is exploring offshore Kenya.

Although the area is seen as predominantly gas rich, companies are also hoping for oil discoveries. Lodge noted that oil seeps were evident on the Tanzanian Island of Pemba.

The recent discoveries have also boosted hopes for development across the region, potentially paving the way for heavy, energy-intensive industry to spring up in impoverished Mozambique and Tanzania.

South Africa's energy minister told a conference in London in June she hoped a gas pipeline could be built to South Africa, helping that country tackle its energy deficit.

The optimism has prompted many big international players such as Britain's BG Group Plc, Italy's Eni SpA,

Norway's Statoil ASA and Texas-based Exxon Mobil Corp to turn their attention to the region.

Nonetheless, there are also several small explorers such as London-listed Dominion Petroleum Ltd and Ophir Energy Plc, which have assets in Tanzania, and Australia's Flow Energy and Pancontinental Oil and Gas NL, which are active in Kenya.

Shares in Dominion rose 8.2 percent.

Analysts predict a rash of consolidation, with bigger players buying the minnows or their assets.

The large potential resource base and need for significant capital investment to complete the development projects should see East Africa become a key focus for the large-cap oils, analysts at Citigroup said last month.

Citigroup Germany Exxon mobil South Africa