The discounters Aldi and Lidl grabbed their biggest share of Britain’s Christmas grocery market to date, while Asda and the Co-op lost out as shoppers sought out bargains to help offset rising household bills.

The German-owned supermarket chains grabbed a 16.8% slice of the market in the four weeks to 28 December, up from 16.3% a year earlier.

In total, shoppers spent £13.8bn on food to take home in the four weeks to 28 December, up 3.8% year on year to £476 each on average.

The highest spending was on fresh meat, which reached sales of £115m, and on chilled snacks such as finger food, dips and antipasti, which hit £80m.

Lidl was the fastest-growing physical chain as Asda and the Co-op lost sales and market share, according to the latest figures from Worldpanel by Numerator, formerly known as Kantar.

Lidl’s rapid growth places it less than one percentage point behind the struggling Morrisons, which it is poised to overtake to become the UK’s fifth largest supermarket.

Aldi – the UK’s fourth largest chain – is snapping at the heels of Asda, where sales fell 4.2% taking its market share to 11.4%, just 1.3 percentage points more than the discounter. Aldi and Lidl have reported record Christmas trading.

However, the upmarket chain Waitrose also posted a strong rise in sales, which were up 4.5% in the three months to 29 December. The online specialist Ocado, which sells Marks & Spencer groceries, increased sales by 15% – indicating some households had plenty of money to spend.

Ocado’s growth was helped as more British households go online for their festive shopping. Total online grocery sales rose by 7.5%, reaching a total share of 12.2% of the grocery market, according to Worldpanel.

However, the figures showed that spending rose at a slower pace than grocery inflation, which eased slightly to 4.3% from 4.7% a month before, indicating that shoppers sought out cheaper alternatives by switching to supermarket own-label products, discount chains and buying fewer items.

Premium own-label sales rose 9% to exceed £1bn for the first time in December, and these products found their way into 92% of shoppers’ baskets.

Inflation was driven by rises in the cost of chocolate, coffee, milk and cream. The price of a traditional tub of chocolates topped £5 for the first time despite average pack sizes shrinking by 5% to 551g.

Fraser McKevitt, the head of retail and consumer insight at Worldpanel by Numerator, said: “It was a Christmas of smart savings and considered choices – almost every household bought into supermarkets’ premium ranges, while price remained front of mind. Discounters enjoyed their biggest ever Christmas share, and shoppers leaned on their loyalty cards to get the best deals.”

Tesco remained the UK’s biggest grocer, with sales up 4.3% to take a market share of 28.7%, ahead of Sainsbury’s, with 16.3%. Both companies will report on Christmas trading later this week.