Tesco's Big Price Drop promotional campaign has hit its share of the UK grocery market, according to the latest data from Kantar Worldpanel.

The country's largest retailer saw its sales increase by 3.8% in the 12 weeks to 27 November. However, the UK grocery market grew by 4.2%, meaning that Tesco accounted for 30.5% of sales, down from 30.7% a year earlier.

Kantar said Tesco was the only one of the UK's big four grocers to see its share of the market fall but said the Big Price Drop campaign had helped the retailer increase the number of shoppers at its stores.

"With more products available for less, the amount of cash taken at the tills has understandably dropped. Despite this, Tesco has successfully attracted more shoppers to its stores through the promotion," Kantar director Ed Garner said.

Asda, the UK's second-largest retailer, saw its sales rise by 5.3%, thanks in part to the integration of the former Netto stores into its estate. Its share of the market inched up from 17% to 17.1%.

Sainsbury's grew in line with the market, with sales up 4.2%, and its market share held at 16.4%.

Sales at Morrisons were up 4.8% and the UK's fourth-largest food retailer saw its share of the market increase from 12% to 12.1%.

Yesterday, the four retailers had to fend off claims by the BBC that they used misleading promotions.

An investigation in conjunction with Which? claimed that some deals offered no value, while others actually cost more than if products were bought separately.