Sainsbury's like-for-like sales including fuel fell 2.4% in the first quarter of 2014, according to the company's trading statement.
Like-for-like sales excluding fuel were down 1.1%.
More top news
An Independence Day event at a UK base has been cancelled by the US Air Force over security fears.
British firms predict the economy should sustain a "solid" pace of growth for the rest of the year thanks to lower oil prices and inflation.
A charity has warned of a "pressure cooker environment" in schools putting children's mental health and self-esteem in danger.