Tesco has increased its dominance of the grocery market from 31.4% a year ago to a record share of 31.8%.
Last month the Competition Commission found that Tesco -which is revealed to have outperformed the market with 6% growth over the year - was not so strong that other retailers could not compete.
Figures from TNS Worldpanel suggest the grocery market is growing at an annual rate of 5%. TNS' Edward Gardner added: "Independents have shown positive sales growth, which is encouraging, but this needs to increase to total market levels if their share is not to be eroded."