Extremely red and dusty galaxies

Preliminary results of a project aiming at unveiling the nature ofthe extremely red galaxies (ERGs) found in deep optical-NIR surveys are presented.Very little is known about these objects, the critical issue beingwhether they are old ellipticals at z > 1 or distant star-forminggalaxies strongly reddened by dust extinction.We expect to shed light onto the unknown nature of these galaxiesby completing our three-step project:(1) the construction of two very deep optical/NIR surveys to select ERGs,(2) subsequent VLT/NIR spectroscopy; (3)observations in the smm region with SCUBA at the JCMT and withMPIfRbolo at the IRAM 30m antenna.