A gas turbine for power plant fed by a dual-fuel source; the gas turbine (1, 1', 20) comprising: - a compressor (3, 3', 29) configured for compressing incoming air; - a dual fuel source configured for selectively delivering gas fuel or oil fuel depending on different operating conditions; - a combustor assembly (4', 22) comprising fuel gas nozzles and fuel oil nozzles configured for feeding fuel gas and fuel oil in the main flow; - a heat exchanger configured for cooling compressed air spilled from the compressor and for feeding this cooled air to a turbine for cooling purpose; - a fuel distribution system comprising an fuel oil line for feeding fuel oil to the fuel oil nozzles and a fuel gas line for feeding fuel gas to the fuel gas nozzles; at least the fuel gas line being provided with at least a valve configured to be closed during oil fuel only operation and a first duct between the last downstream valve and the fuel gas nozzles; - the turbine (5, 5', 21) configured to be driven by the hot gas for performing work on a rotor; wherein the gas turbine moreover comprises a second duct configured for feeding cooled air into the first duct during fuel oil operation wherein the cooled air has a temperature lower than the auto ignition temperature of the fuel gas; wherein the gas turbine moreover comprises: - a control unit configured for operating the gas turbine (1, 1', 20) in fuel oil operation; during fuel oil operation the control unit configured for driving the at least one valve of the fuel gas line to be closed and for feeding the cooled air in the second duct; wherein the control unit being configured for continuously feeding the cooled air in the second duct during fuel oil only operation; characterized in that the second duct is connected downstream to the exit of the heat exchanger so that the cooled air fed in the second duct is part of the cooling air exiting from the heat exchanger; wherein the heat exchanger is configured for cooling the compressed air at a temperature between 320°C and 360°C, preferably at 340°C. - a compressor (3, 3', 29) configured for compressing incoming air; - a dual fuel source configured for selectively delivering gas fuel or oil fuel depending on different operating conditions; - a combustor assembly (4', 22) comprising fuel gas nozzles and fuel oil nozzles configured for feeding fuel gas and fuel oil in the main flow; - a heat exchanger configured for cooling compressed air spilled from the compressor and for feeding this cooled air to a turbine for cooling purpose; - a fuel distribution system comprising an fuel oil line for feeding fuel oil to the fuel oil nozzles and a fuel gas line for feeding fuel gas to the fuel gas nozzles; at least the fuel gas line being provided with at least a valve configured to be closed during oil fuel only operation and a first duct between the last downstream valve and the fuel gas nozzles; - the turbine (5, 5', 21) configured to be driven by the hot gas for performing work on a rotor; wherein the gas turbine moreover comprises a second duct configured for feeding cooled air into the first duct during fuel oil operation wherein the cooled air has a temperature lower than the auto ignition temperature of the fuel gas; wherein the gas turbine moreover comprises: - a control unit configured for operating the gas turbine (1, 1', 20) in fuel oil operation; during fuel oil operation the control unit configured for driving the at least one valve of the fuel gas line to be closed and for feeding the cooled air in the second duct; wherein the control unit being configured for continuously feeding the cooled air in the second duct during fuel oil only operation; characterized in that the second duct is connected downstream to the exit of the heat exchanger so that the cooled air fed in the second duct is part of the cooling air exiting from the heat exchanger; wherein the heat exchanger is configured for cooling the compressed air at a temperature between 320°C and 360°C, preferably at 340°C. wherein the gas turbine moreover comprises a second duct configured for feeding cooled air into the first duct during fuel oil operation wherein the cooled air has a temperature lower than the auto ignition temperature of the fuel gas; wherein the gas turbine moreover comprises: - a control unit configured for operating the gas turbine (1, 1', 20) in fuel oil operation; during fuel oil operation the control unit configured for driving the at least one valve of the fuel gas line to be closed and for feeding the cooled air in the second duct; - a control unit configured for operating the gas turbine (1, 1', 20) in fuel oil operation; during fuel oil operation the control unit configured for driving the at least one valve of the fuel gas line to be closed and for feeding the cooled air in the second duct; wherein the control unit being configured for continuously feeding the cooled air in the second duct during fuel oil only operation; characterized in that the second duct is connected downstream to the exit of the heat exchanger so that the cooled air fed in the second duct is part of the cooling air exiting from the heat exchanger; wherein the heat exchanger is configured for cooling the compressed air at a temperature between 320°C and 360°C, preferably at 340°C.