LONDON, July 2 (Reuters) -

Sainsbury's, Britain's second largest supermarket group, kept its annual financial guidance as it reported a 3% rise in first-quarter underlying sales, though robust grocery sales were partially offset by weather-related weakness in non-food areas.

The group which, with a UK market share of 15.2%, trails only Tesco, said grocery sales rose 4.8% in the 16 weeks to June 22.

However, general merchandise and clothing sales fell 4.3% and sales at the group's Argos business fell 6.2%, reflecting both poor early summer weather which dented sales of seasonal categories and strength in sales in the same period last year.

Sainsbury's said it still expected full-year 2024/25 retail underlying operating profit of between 1.01 billion and 1.06 billion pounds ($1.28-$1.34 billion), which would be growth of 5% to 10%.

"We are pleased with our market-beating grocery performance," Chief Executive Simon Roberts said.

"We've been winning from competitors every month for 15 months, as more and more people are choosing Sainsbury's for their big weekly shop." ($1 = 0.7914 pounds) (Reporting by James Davey; Editing by Kate Holton and Sachin Ravikumar)