* SSEC +0.26%, CSI300 -0.3%

* Securities firms rally on improving fundamentals -analyst

* Sino-U.S. tensions, profit booking limit broader gains

SHANGHAI, Aug 6 (Reuters) - China's benchmark Shanghai Composite Index ended higher for a fifth straight session on Thursday, as a rally in financial and materials stocks offset worries about rising Sino-U.S. tensions that had earlier weighed on the index.

** At the close, the Shanghai Composite index was up 0.26% at 3,386.46, ending higher for a fifth straight day. ** The financial sector sub-index added 1.48%, and securities firms jumped 3.48%. ** The rise was a matter of fundamentals, reflecting signs of improving performance at securities firms, said Zhang Gang, an analyst with China Central Securities. Expectations of possible consolidation in the sector had also boosted interest, he added. ** Materials firms also rallied, led by gold miners as prices of the precious metal touched new highs. Zijin Mining ended 8.78% higher and Juling Gold soared 9.98%. ** But Sino-U.S. tensions continued to weigh on sentiment, while profit-taking pulled down sectors that have rallied in recent days. ** The blue-chip CSI300 index finished down 0.3%, with the consumer staples sector down 2.03% and the healthcare sub-index down 2.84%. ** U.S. President Donald Trump's administration said on Wednesday it was stepping up efforts to purge "untrusted" Chinese apps from U.S. digital networks and called the Chinese-owned short-video app TikTok and messenger app WeChat "significant threats". ** The smaller Shenzhen index ended down 0.62% and the start-up board ChiNext Composite index shed 1.604%. ** Around the region, MSCI's Asia ex-Japan stock index was firmer by 0.25%, while Japan's Nikkei index closed down 0.43%. ** At 07:08 GMT, the yuan was quoted at 6.9464 per U.S. dollar, 0.16% weaker than the previous close of 6.935. (Reporting by Andrew Galbraith; Editing by Kevin Liffey and Ramakrishnan M.)