KNPC said around 30 companies had submitted preliminary bids for Kuwait's planned 615,000 bpd Al Zour refinery, the Middle East's biggest refinery project.

Among applicants were many large international firms, a spokesman for Kuwait National Petroleum Co (KNPC) said. He declined to give any more detail on the bidders.

French firm Technip, US firms KBR, Bechtel and Foster Wheeler and Italy's Snamprogetti had submitted pre-qualification bids which were due by July 3, Kuwaiti daily Al Jarida said.

In May Kuwait doubled the planned budget to $12 billion for the plant, which would be the largest single refinery in the Middle East. Rapidly rising costs in the energy industry have delayed the project and threatened its viability.

The state cancelled a first tender in February after bids came in far above its initial budget. According to local newspaper reports, bids reached as much as $15 billion.

KNPC plans to complete construction of the refinery by end 2011, a year later than the original schedule.

KNPC has said bids for the five engineering, procurement and construction packages would be invited early in the third quarter with a bidding time of around 10 weeks and contracts awarded late in the fourth quarter.

The first package was for oil processing units, the second for hydrogen and sulphur recovery and production, the third for power, steam and water, the fourth for storage and the fifth for marine facilities.

KNPC has contracted engineering and construction company Fluor for project management.

At 615,000 bpd, Al Zour would exceed the capacity of the Middle East's largest refinery, Saudi Arabia's 550,000 bpd Ras Tanura plant. Saudi Arabia plans to build another 400,000 bpd refinery in Ras Tanura.