* Says FY profit forecasts will be "marginally exceeded"

* 5 weeks to Jan. 5 lfl sales up 2.8 pct

* Gross margin maintained at prior year levels

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LONDON, Jan 9 (Reuters) - JD Sports Fashion Plc (JD.L), the British sports and fashion retailer, said on Friday it expected full-year profit to be ahead of market expectations after enjoying positive Christmas trading. "The board now believes that current market expectations for profit before tax and exceptional items [for the year to end-Jan. 2009] will be marginally exceeded," the company said.

Prior to the trading update these stood at 47 million pounds ($71.63 million) to 48 million pounds, up from 43.4 million pounds in the previous year.

For the five weeks to Jan. 3 like-for-like group sales were up 2.8 percent, with the sportswear shops up 1 percent and fashion outlets up 12.5 percent.

Gross margin was maintained at prior year levels, reflecting a decision to defer discounting until Boxing Day.

Like-for-like sales for the 48 weeks to Jan. 3 were up 3.8 percent, with gross margin up marginally.

Shares in JD Sports have lost 26 percent of their value over the last year but have outperformed the FTSE All Share General Retailers Index .FTASX5370 by 1 percent.

They closed Thursday at 205 pence, valuing the business at 99 million pounds. Privately owned Pentland owns 57 percent of the equity.

(Reporting by James Davey; editing by Matthew Scuffham)