[O III]/Hβ vs [N II]/Hα BPT diagnostic diagram for all objects analysed. The demarcations between H II and AGN-ionized regions (Kauffmann et al. 2003; Kewley et al. 2001, dash-dotted and dashed black lines, respectively) are reported. The vertical lines indicate the [N II]/Hαratio for the two sources for which we do not have values of [O III] and Hβemission lines, with the errors shown by shaded bands (the errors are not visible for the SMG Narrow 1 component).