Tesco chief executive Sir Terry Leahy has revealed that discounter Aldi is the rival supermarket chain he admires most in the world.

The revelation drew gasps of surprise from the 200-strong audience gathered at the inaugural World Retail Congress in Barcelona this week.

Sir Terry, who made the keynote speech at the plenary session said Aldi, which has more than 5,000 stores across the globe and sells only own-label, had a grocery offer unmatched by any other chain globally.

"Aldi has a unique formula which has enabled it to achieve a consistent rate of growth over a sustained period of time, he said. "I really admire that."

Sir Terry said Tesco was so successful because it drew lessons from as many different retailers as possible, including Aldi, which it emerged this week is thought to be interested in buying a number of Kwik Save stores when that chain begins a store disposal programme next month. "The trick in this business is to watch everyone and everything and to learn from them quicker than they can learn from you," he added.

Sir Terry also admitted he was impressed by the business models at Ikea and Starbucks. "Who would have thought that what started out as a small chain of American coffee houses would end up being a major player in over 40 different countries in the world," he said.

Sir Terry also gave advice to other retailers on how to succeed in international retailing. He said that businesses would need a flexible approach to entering new markets, patience, and the ambition to be the best local business in each market in which they operated.