TOKYO, Japan - Asia's biggest retailer Fast Retailing Co Ltd left its profit forecast for the year to August unchanged as regular discounts at its Japan-based Uniqlo stores cut average customer spending, undermining strong sales growth.

The company's latest 2012/13 operating profit forecast of 147.5 billion yen ($1.5 billion), which would be up 16.6 percent on the year before, was last raised in January.

Fast Retailing held the guidance steady in April despite signs the economy was picking up under Prime Minister Shinzo Abe's reflationary policies. The company derives the bulk of its earnings from its Uniqlo stores in Japan.

The forecast is in line with an average of 149.7 billion yen expected by 19 analysts surveyed by Thomson Reuters.

Although gains in the stock market have spurred spending on luxury items and boosted earnings at Japan's high-end department stores, results at mass retailers have yet to show a marked increase in broader consumer sentiment and demand.

Fast Retailing also said on Thursday that its operating profit rose 4 percent in the nine months to end-May to 124 billion yen.

Shares of Fast Retailing have jumped 77 percent in the year to date, nearly double the roughly 40 percent rise in Tokyo's benchmark Nikkei average.

Prior to Thursday's announcement, Fast Retailing shares ended 1.8 percent higher at 38,700 yen, against a 0.4 percent rise in the Nikkei.

($1 = 100.1050 Japanese yen)