BPT diagnostic diagram to discriminate between SF- and AGN-ionised regions. The dashed black line and the solid red line show the separations between the two populations according to the boundaries from Kewley et al. (2001) and Kauffmann et al. (2003), respectively. Circles and blue stars mark AGN- and SF-dominated regions, respectively. Plots are colour-coded according to how far bins are from the centre. We have not investigated the regions located between the two lines (purple circles).