Qatar Petroleum International (QPI) plans to buy a 25% stake in the US$4 bln Long Son petrochemical project in Vietnam, as per senior executive of Petrovietnam as reported by Reuters. "We will establish a joint venture to build the complex," Do Van Hau, Petrovietnam chief executive officer said after signing an investment agreement with QPI officials. Detailed work on the joint venture will start next month. The complex will be Vietnam's first fully integrated petrochemical project, consisting of upstream, intermediate and downstream plants, QPI said. The venture comprises Petrovietnam, Vietnam's Vinachem, SCG Chemicals and Thai Plastics and Chemicals Co Pcl.