China will impose duties on oil exported by foreign partners in offshore oil production joint ventures if contracts with Chinese partners are signed after August 1, said sources with the Ministry of Finance (MOF) Tuesday.

   Contracts already signed will be free from export duties until August 1, 2012, according to a circular jointly released by the MOF and the General Administration of Customs on Tuesday.

   The announcement is a new move by the Chinese government to curb exports of crude oil after the country imposed a five percent export duty starting last November.

   The export duty rate on foreign companies' interest oil shares will be the same as domestically produced crude oil, which is five percent at present, said sources with the MOF.

   Export duties reduced China's crude oil exports by 36.6 percent year-on-year to 1.6 million tons in the first five months.

   China's net imports of crude oil rose by 11.5 percent to 65.8 million tons in the first five months of the year.