MELBOURNE: Top global miner BHP Billiton signaled caution over a sustained global recovery and held off from a share buyback after reporting its weakest first-half profit in four years.

BHP's July-December profit nevertheless beat market forecasts and was 24 percent stronger than in the previous half, spurring the miner to raise its dividend slightly, pushing its shares up more than 3 percent.

"The momentum's the important factor," said Tim Schroeders, a portfolio manager at Pengana Capital.