LONDON, Oct 1 (Reuters) - Britain's J Sainsbury cut its full-year sales forecast on Wednesday after trading fell sharply in the second quarter, dragged down by competition in a UK grocery market growing at its slowest pace for more than 20 years.
The group, which trails troubled market leader Tesco and is battling with Wal-Mart Stores' Asda to be the UK's No. 2 grocer, said sales at stores open a year fell 2.8 percent, excluding fuel, in the 16 weeks to Sept. 27, its fiscal second quarter.
That compared to analysts' forecasts of down 3-4 percent and a fall of 1.1 percent in the first quarter.
The trading update is the first to be presented by new Chief Executive Mike Coupe, who succeeded Justin King in July.
Sainsbury's total second quarter sales fell 0.8 percent, excluding fuel.
The firm said it now expected its like-for-like sales in the second half of the year to be similar to the first half. Previously it was forecasting a small rise. (Reporting by James Davey; editing by Kate Holton)