Discount grocer Lidl is splashing the cash on advertising and was the highest spender among its rivals for the third consecutive month in May.

Lidl spent £5.1m on TV and press advertising in the four weeks to May 23, a 320% rise on the same period last year, Nielsen figures revealed today. Its nearest rival was Asda with a £4.8m spend. Marks & Spencer is also significantly upping its spend on ads, up 131% to £1.8m last month. It was the third biggest spender.

Meanwhile sales volumes across the supermarket sector rose for the sixth straight month in May, but revenue was down as food price deflation stayed at a record low.

Volumes increased 0.5% in the four weeks to the end of May. However the value of sales at the till fell 0.5% in the same period.

May’s cool weather meant packaged food benefited as sales volumes rose 0.9%. But meat, fish & poultry (-3.2%), dairy (-2.4%) and produce (0.9%) all suffered.

In the 12 weeks to May 23, only Tesco (-1.7%) and Asda (-2.6%) reported drops in year-on-year sales by value among the 10 biggest supermarkets. Sales at Sainsbury’s and Co-operative were flat, while the other six all experienced year-on-year growth – led by the discounters Aldi (20.5%) and Lidl (8.6%).

Kantar figures earlier this week revealed that Morrisons was the only grocer of the big four to see grocery sales grow in the 12 weeks to May 24.

Looking ahead, Mike Watkins, Nielsen’s UK head of retailer and business insight said: “With consumer confidence at a nine-year high and a growing economy, food retailers’ fortunes should gradually improve, with summer providing a further boost to spending intentions.”

He added: “Modest increases in advertising spend are also expected. However, more than ever, supermarkets need to work harder to ensure their messages cut through and resonate with shoppers, providing reasons beyond just lower prices.”