Saudi Aramco is likley to invite firms to help develop Manifa oilfield, with a potential production of 900,000 barrels of oil a day, this month.

Aramco plans to invite prequalified companies to bid for an estimated $3 billion worth of contracts on the company's largest-ever offshore project, a report in the Gulf Daily News said quoting sources familiar with the company's plans.

The estimated $10 billion Manifa development programme aims to add 900,000 barrels a day of heavy crude, 120 million cubic feet a day of gas and 50,000 barrels a day of condensate to Aramco's production by mid-2011.

Manifa's heavy crude will be exported from Aramco's Al Juaymah and Ras Tanura terminals in eastern Saudi Arabia.

The gas and the condensate will be processed at the Khursaniyah gas plant.

The project also includes construction of four pipelines, a water supply system and oils and gas processing facilities.

The tender documents for the project were originally due to be released in June or July but have been delayed without explanation, sources said.

Companies including Bechtel, Fluor Corporation, JGC Corporation and Technip in late May submitted prequalification documents.

In February, Aramco awarded an estimated $1bn contract to Belgium contractor Jan De Nul for the Manifa project's offshore portion, covering dredging works in the Gulf.