A burner for a gas turbine engine is provided. The burner includes a radial swirler for creating a swirling fuel/air mix, a combustion chamber where combustion of the swirling fuel/air mix occurs, and a pre-chamber located between the radial swirler and the combustion chamber. The radial swirler includes a plurality of vanes arranged in a circle, generally radially inwardly extending flow slots are defined between adjacent vanes in the circle, each flow slot includes a radially outer inlet end, a radially inner outlet end, first and second generally radially inwardly extending sides provided by adjacent vanes, and a base and top. A flow slot includes a first gas fuel injection hole in its base and a flow slot includes a second gas fuel injection hole in its first side wherein the amounts of gas fuel injected via the first and second gas fuel injection holes are independently variable.