Tesco’s market share has dropped to its lowest point in almost seven years, according to new data from Kantar Worldpanel.

The UK’s largest supermarket accounted for 29.9% of the market in the 12 weeks to 22 January 2012. The news marks the first time its share has dipped below 30% since May 2005, when it recorded share of 29.7%, and is down from 30.5% for the equivalent period a year ago.

By contrast, Asda saw its share increase from 16.9% a year ago to a new high of 17.5%, while Sainsbury’s held on to its largest slice of the action since March 2003, with 16.7% of UK grocery sales.

Iceland also posted its best performance in a decade, grabbing 2.1% of the market.

“The completion of the Netto conversion has led to an all-time record performance for Asda,” said Kantar’s Edward Garner.

“In contrast, there is considerable pressure on Tesco, with its growth rate of 2.1% only half the total market average.  This has caused its share to fall by 0.6 percentage points.”

“Iceland’s share is at its highest for 10 years as shoppers continue to manage down their spending.  With bids for the chain closing today, these figures are promising for potential buyers and show the importance of a good value-for-money message in today’s grocery market.”

The market as a whole grew by 4.2% over the period, well behind the 5.7% rate of inflation calculated by Kantar.