Qld hiker missing in heat without water

Grave concerns are held for a Queensland hiker missing in severe heat without any water.

An air and land search is underway to find the man, aged in his 40s, who told emergency services over the phone he was lost on Mount Barney and had no water before his mobile ran out of battery.

Police were advised of the man's disappearance around 12.30pm on Saturday and hold grave concerns for his safety as heatwave conditions sweep southern Queensland.