A burner for burning fuel in an oxidant having a fuel nozzle sandwiched between upper and lower oxidant nozzles. The fuel nozzle and upper and lower oxidant nozzles produce fuel and oxidant jets of outwardly divergent, fan-shaped configuration to provide a wide uniform flame and thus the elimination of hot spots. Upper and lower secondary oxidant nozzles can be provided in staged combustion such that fuel is burned and oxidant supplied by the upper and lower oxidant nozzle means in the substoichiometric ratio and then combustion is completed by oxidant supplied by the secondary upper and lower oxidant nozzles. In another aspect, a nozzle is provided in which a passageway is divided in a lengthwise direction and thus the flow of oxidant flowing through the passageway is divided into a plurality of subflows of equal velocity and of gradually divergent configuration to prevent the decay of a fan-shaped flow of oxidant from the nozzle.