SHANGHAI, May 7 (Reuters) - China stocks fell on Friday to end the week lower, as worries over lofty valuations and Sino-West tensions offset optimism surrounding data and survey pointing to a continued recovery in the world’s second-largest economy. ** The blue-chip CSI300 index fell 1.3% to 4,996.05, while the Shanghai Composite Index slipped 0.6% to 3,418.87 points. ** For the shortened week, CSI300 declined 2.5%, while SSEC dipped 0.8%. ** The tech-heavy start-up board ChiNext dropped 3.5%, having lost 5.9% for the week. ** Analysts remain cautious for the time being, citing a lack of factors for any upside momentum, and noting lofty valuations in some parts of the market. ** Investors need to watch more and take less action now, as the pressure is mounting for a short-term correction in the main board, said Yan Kaiwen, an analyst with China Fortune Securities. ** AVIC Securities noted in a report that valuations of equities are under pressure as China is tightening its monetary, credit and fiscal policies. ** The brokerage added that China would continue to maintain policy stability as the latest Politburo meeting refrained from mentioning stabilizing leverage and commodities prices. ** Tensions between China and the West have become another point of concern for investors. ** Bucking the broad retreat, banking and materials stocks gained ground due to data pointing to China’s solid economic recovery. ** The CSI300 banks index and the CSI300 materials index rose 1.1% and 1.8% on Friday. ** China’s export growth unexpectedly accelerated in April as the brisk U.S. recovery and stalled factory production in other countries hit by the coronavirus propped up demand for goods made in the world’s second-largest economy. ** China’s services sector expanded at the sharpest pace in four months in April, driven by fast growing new businesses, a private survey showed on Friday, although surging costs are likely to weigh on growth over the coming months. (Reporting by Shanghai Newsroom, Editing by Sherry Jacob-Phillips) Our Standards: The Thomson Reuters Trust Principles.