Abstract: There is provided a gas-fuelled burner for producing a concentrated, rotag flame. The burner comprises a body including a plenum chamber into which gas and primary combustion air are introduced by a standard nozzle, which chamber is defined and delimited on its upper side by a roof element provided with a plurality of relatively narrow passgeways for the gas/air mixture, the passageways leading from the plenum chamber upwards and inwards to the upper, outside face of the burner. The passageways include angles with a common plane perpendicular to the vertical axis of the burner, and individual vertical planes substantially passing through the passageways are tangential to an imaginary vertical cylinder passing through the center of the burner.