NEW DELHI: The chairman of India's Tata Sons, N Chandrasekaran, said on Wednesday (Aug 12) that he has resigned in light of the lack of board approval for his reappointment amid tensions with the charity arm that controls the salt-to-aviation Tata Group. Tata Sons controls more than 30 companies in the conglomerate, including Tata Consultancy Services (TCS), Tata Motors and Air India, but is in turn 66 per cent owned by Tata Trusts, the group's charitable arm. In February, Tata Sons postponed a decision on reappointing Chandrasekaran as chairman after Noel Tata, chairman of Tata Trusts, opposed the move. "Tata Sons is a very large institution and there are many strategic projects that are under critical stages of execution," he added. The disagreements between Chandrasekaran and the Tata Trusts were the sole reason for his resignation, said a source with direct knowledge of his decision.