BEIJING/SHANGHAI, March 4 (Reuters) - Hong Kong shares dropped on Thursday, weighed down by losses in material and tech stocks, as equities globally retreated on renewed doubts over monetary support after another rise in U.S. Treasury yields. ** At the close of trade, the Hang Seng index was down 643.63 points, or 2.15%, at 29,236.79. The Hang Seng China Enterprises index fell 2.92% to 11,325.58, reversing course a day after its biggest one-day gain in six weeks. ** The sub-index of the Hang Seng tracking tech shares dipped 5.8%, while the IT sector dropped 5.3%, and the material sector ended 6.4% lower. ** Global bond yields have risen in recent weeks, with markets concerned that central bankers could tighten the monetary spigot as the global economy rebounds from the damage caused by the COVID-19 pandemic. That prospect hit world equities last week. ** The top gainer on the Hang Seng was BOC Hong Kong Holdings Ltd, which gained 2.47%, while the biggest loser was WuXi Biologics Inc, which fell 10.16%. ** China’s main Shanghai Composite index closed down 2.05% at 3,503.49 points, while the blue-chip CSI300 index ended down 3.15%, its worst daily performance in more than seven months on sell-off of high valuation stocks. ** Around the region, MSCI’s Asia ex-Japan stock index was weaker by 1.9%, while Japan’s Nikkei index closed down 2.13%. (Reporting by Cheng Leng in Beijing and Andrew Galbraith in Shanghai; Editing by Aditya Soni)