The Chinese probe into financing of copper and aluminium may spread to other commodities such as iron ore and soybeans, an executive of a commodity hedge fund said on Wednesday. Banks and trading houses have been making urgent checks on the security of metal holdings in China, sparked by a suspected fraud at Qingdao Port, the world's seventh biggest. Police are investigating the duplication of warehouse receipts by a third-party firm on metal cargos used to obtain financing. "I would say it's going to spill over from copper into iron ore, into soybeans. A huge amount of apparent demand in China is through shadow financing and holding stocks so you can have the cash…