SHANGHAI, Jul 29 (SMM) - Copper inventories in domestic bonded zones decreased by 10,200 mt from last Friday July 22 to 266,100 mt as of July 29, according to the SMM survey. Inventory in the Shanghai bonded zone dipped 7,800 mt to 241,700 mt, and inventory in the Guangdong bonded zone fell 2,400 mt to 24,400 mt. The improvement of the SHFE/LME price ratio and the high premiums in China boosted the demand for customs declaration. Sellers were active in finding sources of warrants and bills of lading that arrived at ports in recent days, hence the Yangshan copper premiums rebounded sharply and the demand for customs declaration grew significantly, resulting in the decline in bonded zone inventory this week.