UK supermarket chain Tesco now has a record 29% of the UK grocery retail market, according to the latest industry data from market researcher TNS.

Tesco's market share increased to 29% in the 12 weeks to 2 January, compared to 28.7% a month earlier and 26.6% in the year-ago period, reported Reuters.

Supermarket group Wm Morrison continued to leak market share after its takeover of rival chain Safeway. The combined market share of Morrisons and Safeway was 12.4% in the 12-week period, compared to 12.8% a month earlier and 14.5% in the year-ago period.

But there was better news for struggling supermarket chain Sainsbury, which increased its market share to 15.9% in the 12-week period, from 15.6% a month earlier. However, its share was still down compared to the 16.3% it had in the year-ago period.

"Sainsbury, while not setting any records, has slowed its rate of decline...Christmas is traditionally a strong period for the outlet and the share duly rose for the fourth period in succession," Edward Garner, communications director of TNS Superpanel, was quoted by Reuters as saying.

Meanwhile, the UK's second-largest grocer, Asda, owned by US retail titan Wal-Mart, recorded a market share of 17.1% in the latest period, compared to 16.8% a month earlier and 16.7% in the year-ago period.