KHOBAR, Saudi Arabia, Oct 23 (Reuters) - State oil giant Saudi Aramco SDABO.UL has extended the deadline to bid for the upgrade of its 124,000 barrels per day Riyadh refinery by ten weeks to January, two industry sources said on Tuesday.

Companies are now due to bid by Jan. 7 from Oct. 20 for the project, estimated to cost around $300 million, to produce cleaner fuels. ID:nL6E8K33KE

"Bidders requested bidding (deadline) to be extended," said one source close to the process.

The world's top oil producer has embarked on a programme to upgrade its refineries to produce cleaner fuels.

It spent $2 billion for a clean fuels project at its joint venture refinery with U.S.-based Exxon Mobil XOM.N due to be operational in 2013. The project is expected to cut sulphur content for gasoline by 2013 and for diesel by 2016.

The second phase of the upgrade involves plans to start cleaner fuels and aromatics production at its largest crude oil refinery in Ras Tanura by 2016. ID:nL5E8GO2B2

(Reporting by Reem Shamseddine, Editing by Humeyra Pamuk)

((Reem.Shamseddine@thomsonreuters.com)(+96638592898)(Reuters Messaging: reem.shamseddine.thomsonreuters.com@reuters.net))

Keywords: ARAMCO RIYADH/BIDS