By James Davey

LONDON (Reuters) - A better-than-expected Christmas performance from British sportswear and fashion retailer JD Sports Fashion (JD.L) reflected a cut in competitor capacity and a strong product proposition, its chief executive said.

JD Sports shop

The firm said it would "significantly exceed" market expectations for year to end-January 2010 pretax profit after posting a 6.6 percent rise in like-for-like sales in the five weeks to January 2, which took the cumulative increase for the 48 weeks to January 2 to 2.7 percent.

Peter Cowgill told Reuters JD benefited from store closures by JJB Sports (JJB.L), which came close to administration in 2009, as well as capacity reductions from smaller rival USC.

He said exclusive product from external brands such as Nike and Adidas, as well as the increasing popularity of owned brands, such as McKenzie and Carbrini, had also provided a boost.

"Once again the buyers have got it right ... We've done very well on footwear again, and in men's textiles we've had a good run because of the brand differentiation that we offer."

Although, like other retailers, Cowgill is concerned by the prospect of tax rises after a general election that must be held by June, he is hopeful the soccer World Cup will be a fillip to sales.

"If we (England) do well there's a feelgood factor in the sports leisurewear industry which tends to permeate, so we're a little bit optimistic about that," he said. Investec, JD's house broker, raised its current year pretax profit forecast by 12.5 percent to 63 million pounds -- a move Cowgill said he was comfortable with.

Shares in JD, 57 percent of which are owned by sportswear company Pentland, were up 10.9 percent at 607.5 pence by 11:45 a.m., valuing the business at 297 million pounds.

The stock has nearly trebled over the last year.

(Editing by Mark Potter)