International investors have extended their inroads into China’s commercial property sector this year, as the largest cities become hunting grounds for office towers, shopping malls and mixed-use projects.Global investors have splashed out 29.2 billion yuan (US$4.35 billion) in the first three months on properties in Shanghai, a huge jump from 9.1 billion yuan a year ago, according to real estate service firm Cushman & Wakefield. In Beijing, offshore investors accounted for 56 per cent of the…