LONDON, June 9 (Reuters) - British retailer JD Sports Fashion (JD.L) said the build-up to the soccer World Cup, which starts on Friday 11 June, had helped to boost sales in recent weeks and reported a return to growth at its fashion business.

JD SPorts - Photo: www.jdsports.co.uk

The group, which trades as JD Sports, Chausport, Size, Bank and Scotts from over 530 stores, said on Wednesday 9 June sales at UK and Irish shops open at least a year rose 4.1 percent in the 18 weeks to June 5.

That was up from the 2 percent increase reported after the first 10 weeks of the period.

Sports store sales growth accelerated to 5.1 percent from 3 percent, while fashion store sales were down 1.2 percent, improving from a 3.5 percent decline and showing growth over the last eight weeks of the period.

Profit margins across the group were encouraging, it said in a brief trading update.

JD Sports shares have outperformed the UK general retailers' index .FTASX5370 by about 80 percent this year. They closed at 781 pence on Tuesday 8 June, valuing the business at about 383 million pounds ($592 million). (Reporting by Mark Potter; Editing by Erica Billingham)