An oxy-fuel burner comprising: a central burner element comprising: a central conduit having a central axis and terminating in a central nozzle ; and an annular conduit terminating in an annular nozzle surrounding and coaxial with the central conduit , the annular conduit 30) and the central conduit being separated by an annular wall; the central conduit being arranged to flow a first reactant (R1) and the annular conduit being arranged to flow a second reactant (R2); a first staging conduit spaced apart from a side of the central burner element and terminating in a first staging nozzle ; a second staging conduit spaced apart from an opposite side of the central burner element and terminating in a second staging nozzle ; a first mechanism arranged to apportion a flow of the second reactant (R2) into a non-zero primary flow of the second reactant directed to the annular conduit and a non-zero secondary flow of the second reactant; wherein one of the first and second reactants (R1, R2) is a fuel and the other of the first and second reactants (R1, R2) is oxygen, characterized in that the oxy-fuel burner further comprises a second mechanism arranged to selectively apportion the secondary flow of the second reactant (R2) between the first staging conduit and the second staging conduit , wherein the first mechanism comprises a variable flow restriction to regulate the primary flow of the second reactant (R2) to the annular conduit , thereby indirectly regulating the secondary flow of the second reactant (R2) to the second mechanism in a complimentary manner, and wherein the second mechanism comprises a valve to selectively direct the flow of the second reactant (R2) between the first staging conduit and the second staging conduit . a central burner element comprising: a central conduit having a central axis and terminating in a central nozzle ; and an annular conduit terminating in an annular nozzle surrounding and coaxial with the central conduit , the annular conduit 30) and the central conduit being separated by an annular wall; the central conduit being arranged to flow a first reactant (R1) and the annular conduit being arranged to flow a second reactant (R2); a central conduit having a central axis and terminating in a central nozzle ; and an annular conduit terminating in an annular nozzle surrounding and coaxial with the central conduit , the annular conduit 30) and the central conduit being separated by an annular wall; the central conduit being arranged to flow a first reactant (R1) and the annular conduit being arranged to flow a second reactant (R2); a first staging conduit spaced apart from a side of the central burner element and terminating in a first staging nozzle ; a second staging conduit spaced apart from an opposite side of the central burner element and terminating in a second staging nozzle ; a first mechanism arranged to apportion a flow of the second reactant (R2) into a non-zero primary flow of the second reactant directed to the annular conduit and a non-zero secondary flow of the second reactant; wherein one of the first and second reactants (R1, R2) is a fuel and the other of the first and second reactants (R1, R2) is oxygen, characterized in that the oxy-fuel burner further comprises a second mechanism arranged to selectively apportion the secondary flow of the second reactant (R2) between the first staging conduit and the second staging conduit , wherein the first mechanism comprises a variable flow restriction to regulate the primary flow of the second reactant (R2) to the annular conduit , thereby indirectly regulating the secondary flow of the second reactant (R2) to the second mechanism in a complimentary manner, and wherein the second mechanism comprises a valve to selectively direct the flow of the second reactant (R2) between the first staging conduit and the second staging conduit . <EOS>