We identify eight z > 1 radio sources undetected at 850 \mu m but robustly detected at 70 \mu m , confirming that they represent ultraluminous infrared galaxies ( ULIRGs ) with hotter dust temperatures ( < T _ { d } > =52 \pm 10 K ) than Submillimetre Galaxies ( SMGs ) at similar luminosities and redshifts .
These galaxies share many properties with SMGs : ultra-violet ( UV ) spectra consistent with starbursts , high stellar masses and radio luminosities .
We can attribute their radio emission to star formation since high-resolution MERLIN radio maps show extended emission regions ( with half light radii of 2-3 kpc ) , which are unlikely to be generated by AGN activity .
These observations provide the first direct confirmation of hot , dusty ULIRGs which are missed by current submillimetre surveys .
They have significant implications for future observations from the Herschel Space Observatory and SCUBA2 , which will select high redshift luminous galaxies with less selection biases .