Jamar Rogers -- a finalist on Season 2 of "The Voice" who was diagnosed with HIV in 2006 -- is in intensive care in an L.A. hospital after suffering a lung infection.
TMZ spoke with Jamar's rep who tells us ... the 31-year-old was admitted to the hospital on September 3rd at the urging of his manager.
But the rep says Jamar's health took a turn for the worse ... and on Monday he was listed in critical condition.
Jamar's rep tells us several friends and family members have reached out to the singer -- including his former "Voice" coach Cee Lo Green.
We're told doctors expect Jamar to remain hospitalized for at least another week or so.