Supermarket giant Tesco saw strong sales in the third quarter as its Clubcard reward scheme helped it draw in customers and it continued to benefit from increasing non-food sales.UK like-for-like sales excluding petrol and VAT were up by 2.8%, in line with analyst expectations. New stores in the UK contributed 2.9% to growth, bringing total sales growth excluding petrol to 5.7%.Tesco said customers were responding well to offers which double the number of points on their Clubcards. Non-food sales growth was driven by toys and electrical and entertainment products, it said.Tesco Direct, the online sales business, also delivered a strong performance, said Tesco, which said recently that it would be opening 'dark stores', where staff do all the shopping for online customers.Tesco, which operates the Fresh & Easy grocery chain in California as well as stores in mainland Europe, said the international like-for-like sales trend had improved, with like-for-like sales down by 3.7% in the quarter compared with 6.7% in the second quarter.Tesco said it is performing in line with expectations with the outlook for the year unchanged.'We are seeing improving customer confidence and encouraging trends in both the UK and our international businesses, although recessionary conditions still exist in a number of markets,' said chief executive Terry Leahy.