First 450 

Aims. In an effort to make progress in the current debate on the earliest phases of massive star formation, we took a census of Class 0-like protostellar dense cores in the NGC 3576 region, one of the nearest and most luminous embedded sites of high-mass star formation in the Galaxy. Methods. We used the P-ArTéMiS bolometer camera on the APEX telescope to produce the first 450 μm dust continuum map of the filamentary dense clump associated with NGC 3576. Results. Combining our 450 μm observations with existing data at other wavelengths, we identified seven massive protostellar sources along the NGC 3576 filament and placed them in the Menv–Lbol evolutionary diagram for protostars. Conclusions. Comparison with theoretical evolutionary tracks suggests that these seven protostellar sources will evolve into massive stars with masses $M_\star \sim 15$–50 $M_\odot$. Four sources are classified as candidate high-mass Class 0 objects, two sources as massive Class I objects, and one source appears to be at an intermediate stage