Using small-angle light scattering we show that a new phase of soot with size ca. 10 mum and a fractal dimension of D similar or equal to 2.6 exists in laminar diffusion flames for a wide range of heavily sooting fuels. This new phase appears to be a supramicrometer extension of the well-known submicrometer, D similar or equal to 1.8 phase of soot formed via diffusion-limited cluster aggregation (DLCA). The occurrence of this new soot phase correlates with an empirical sooting index for fuels. This supports a creation scenario in which these supramicrometer aggregates are created via a percolation of the submicrometer, D similar or equal to 1.8 aggregates.