The investment bank Credit Suisse First Boston has cut its rating on SABMiller to "underperform" from "neutral" with a 480 pence share price target.

Although the bank's analysts said the strong rand would boost first-half results, they said this was already priced in and the shares were currently expensive.

In a research note Credit Swiss said: "Miller Lite is driving the recent gains, but the turnaround is not yet in sight."

It continued: "AC Nielsen supermarket data for August and September shows a sizeable up-tick in Miller Lite's performance. While this coincides with new low carb ads, we believe it is more a function of increased short-term promotional activity and is not sustainable."