TOKYO, April 9 (Reuters) - Fast Retailing (9983.T) reported 28.7 percent growth in operating profit on Thursday 9 April for the six months ended in February, buoyed by robust sales at its Uniqlo casual clothing chain, and again lifted its operating profit forecast for the full year to August.

Uniqlo Spring 2009

The company has become a rare bright spot amid a worsening retail slump, as Uniqlo has attracted thrifty consumers with low-price but quality basic garments while also rolling out hit products like its "Heattech" line of heat-trapping inner wear.

Same-store sales at Uniqlo stores in Japan posted a hefty 12.9 percent growth for the firm's business first half, comfortably beating its revised-up forecast of a 9.6 percent increase.

The firm, which runs more than 800 Uniqlo stores at home and overseas including China and Britain, said its operating profit came to 69.9 billion yen ($701 million) for the first half to Feb. 28, up from 54.3 billion yen a year earlier.

For the year ending in August, the firm forecast an operating profit of 101 billion yen, up 15.4 percent from a year earlier. That compares with a mean forecast of 105.4 billion yen in a poll of 15 analysts by Reuters Estimates.

Shares of Fast Retailing have risen 20 percent in the past 12 months, outperforming a 33 percent decline in the benchmark Nikkei average .N225. (Reporting by Taiga Uranaka)