Police are searching the Brisbane River for a missing man who disappeared while rowing on Wednesday morning, leaving an upturned boat behind.

Three rowers were on the river at West End about 4.40am when the 63-year-old man became separated in the dark.

Police are searching the Brisbane River for the missing man. Credit:Jorge Branco

Police were still clinging to hope of finding the man despite strong currents and the length of time he had been missing.

Acting Inspector Don Dunstan said they entered the river at Commercial Rowing Club at South Brisbane before heading upstream.