An ongoing Chinese investigation will again delay what could be the world’s largest-ever mining merger between Glencore (GLEN.LON, 0805.HKG) and Xstrata (XTA.LON), Reuters reported. Glencore said Tuesday that it would push the closing date for its $35 billion acquisition of Xstrata to May 2. Although the company said it was in constructive dialogue with China’s Ministry of Commerce (MofCom), it said that regulatory approval would not come in time for the April 16 deadline. Glencore said in March that the MofCom investigation focused on copper. Both Glencore and Xstrata are based in Switzerland.