Australian wineries have been advised by their most important single customer to use screw-top closures not corks for wines meant to be drunk within three to four years. Phil Reedman, product development manager of the UK's supermarket chain Tesco, said screw-top was the best possible closure.

He was speaking to journalists after taking part in a 340-wine tasting organised by Australia's leading consumer magazine, Winestate. Consumer evidence was unreliable, Reedman said adding: "We do internal tastings and I'm confident that the real number of wines that are (cork) tainted is about 5%."

He added: "The other thing that Australia should be doing is really considering the impact of viticulture on the environment to ensure that what you are doing is sustainable. I'm not convinced that your practices are sustainable in all areas."

Tesco is the largest buyer of Australian wine in the world, shipping more than 2.5m cases a year.