Beam Global in the US says no new supplies will be released until November when the current ageing stock reaches its nine-year minimum requirement.

The company says the situation has been caused by double-digit growth exceeding forecasts made in 2000.

Bill Newlands, president of Beam Global Spirits & Wine US, said: "We could bottle the next batch a tad earlier to satisfy demand but that just wouldn't be right.

"Much as we want to keep product available, we would never compromise on quality, or bottle at lower proof to fill a short-term gap."

"We have to thank our growing ranks of Knob Creek fans for making it so, and to ask for their patience while the next batch fully matures to age nine."