Sources close to the bidding process said the two firms were finalizing their proposals and await a final word from the partners in the project, which will be located in Jubail on the Gulf coast.

“Daelim is still lowest for the [mixed feed] cracker,” said one source.

Another source said there was a slight difference in prices between the competing firms.

A spokesman for Daelim said the company joined the bidding process but did not provide further details.

GS was second lowest, France Technip came third and Samsung Engineering fourth, said another source.

The cost of the project, still called Ras Tanura Integrated Project (RTIP) as it was to be integrated with an expansion of the Ras Tanura refinery, is around $20 billion, Aramco’s chief executive Khalid Al-Falih said in December.

Aramco has floated the bids for the project with Dow and another expansion of a joint venture with Japan’s Sumitomo Chemical but would only make a final investment decision sometime this year.

The Dow-Aramco project, which would be one of the largest in the world, is part of the Saudi firm’s ambition to develop its petrochemical industry as the kingdom seeks to move away from over-reliance on oil revenues.

Rabigh II and the new complex with Dow are set to almost double Saudi Aramco’s chemicals manufacturing capacity and would add a number of products.