UPDATE 1-Qatar buys stakes in Shell Chemicals jv in Singapore

* Qatar Petroleum, Shell set up chemical venture in Singapore

* Shell to sell stakes in PCS and TPC to Qatar Petroleum

* Qatars first overseas downstream acquisition, more to come (Adds details, background)

By Felicia Loo and Judy Hua

SINGAPORE, Nov 11 (Reuters) - Qatar Petroleum International (QPI) and Shell Eastern Petroleum Pte Ltd have sealed agreements in which QPI takes stakes in two Shell Chemicals joint ventures in Singapore, its first overseas downstream acquisition, the companies said on Wednesday.

Under the deal, to be completed by December, Shell will sell its existing shareholdings in two companies to a new joint venture called QPI and Shell Petrochemicals (Singapore) Pte Ltd (QSPS).

Through the venture, QPI and Shell (RDSa.L) will effectively hold 50 percent of the Petrochemical Corporation of Singapore (PCS) and 30 percent of The Polyolefin Company (Singapore) Pte Ltd (TPC).

"Qatar Petroleum's goal is to become a major player in the global energy industry," said Qatari Minister of Energy and Industry Abdullah al-Attiyah in a statement.

"Qatar is a significant and fast-growing producer of chemical feedstocks. Extending our reach further into petrochemicals in the crucial Asia-Pacific region will help us achieve our ambitious global goals."