SHANGHAI, Sept 10 (Reuters) - Shanghai stocks witnessed their biggest weekly gain in seven months and closed up on Friday, after U.S. President Joe Biden and his Chinese counterpart Xi Jinping’s “candid” conversation. The Shanghai Composite Index gained 0.3% to 3,703.11 points, while the blue-chip CSI300 index rose 0.9%, to 5,013.52. ** The Shanghai Composite Index jumped 3.4% for the week, while the CSI300 index surged 3.5%, also logging its best weekly performance since June. ** Biden and Xi spoke on the phone for the first time since February, and discussed the need to avoid letting competition between the world’s two largest economies veer into conflict, a senior U.S. official said. ** The official said the tone of their conversation was both “familiar” and “candid”, and Chinese state media described it as “a broad, candid, in-depth and strategic conversation.” ** The semiconductors sub-index led the gains on the Chinese market, jumping 4.4%. ** A sub-index tracking brokerages rose 1.2% to its highest in nearly eight months amid China’s plan to set up a new bourse in Beijing. Banks gained 2.4%. ** The energy sub-index slumped 4.1% after China’s state reserves administration said it would release crude oil reserves to the market via a public auction to ease the pressure of high feedstock costs on domestic refiners. ** The automobiles sub-index lost 1.1%, after industry data on Friday showed China’s vehicle sales slid 17.8% in August from a year earlier. (Reporting by Shanghai Newsroom; Editing by Jan Harvey) Our Standards: The Thomson Reuters Trust Principles.