Johannesburg - South African high-end retailer Woolworths Holdings reported double-digit growth in food and clothing sales for the first half of the year, a sign that spending remains robust among wealthier consumers.

However, investors were likely looking for an even stronger performance and its shares sank more than 2 percent.

Woolworths, which sells products similar to those of Britain's Marks and Spencer, said clothing sales in its home market rose by 10.7 percent in the 26 weeks to December 29.

Food sales in South Africa increased by 15.3 percent, while sales in Australia and New Zealand were nearly 30 percent higher in Australian dollar terms.

Thanks to its reliance on middle-class shoppers, Woolworths is more resilient to the weak growth and high household debt levels that have squeezed lower-income consumers.

Massmart Holdings, the South African unit of Wal-Mart Stores Inc, surprised the market on Wednesday with a near 10 percent rise in annual sales, slightly above analyst estimates.

Retailers in Africa's biggest economy came under pressure in 2013 on worries about weakening consumer spending.

Official data showed on Wednesday that retail sales jumped 4.2 percent year-on-year in November, well above the 1 percent growth economists polled by Reuters had expected.

Shares of Woolworths were down 2.3 percent at 71.69 at 16:41 SA time. - Reuters