BP Plc has won a bid to operate ONGC's giant Mumbai High oil and gas field by offering up to 60 per cent increase in output over baseline, the state-owned firm said on Wednesday.State-owned Oil and Natural Gas Corporation (ONGC) had in June last year floated a tender seeking foreign partners to reverse declining output at its flagship Mumbai High fields, offering a share of revenue from incremental production plus a fixed fee but not any equity stake.