Retailers in the 16 nations using the euro saw their sales fall in May, renewing a slump that was broken in April by a short-lived improvement, according to official EU data.

The volume of retail sales in the eurozone dipped 0.4 per cent in May over one month and 3.3 per cent over one year, the European Union's Eurostat data agency said.

The result wiped out a minor improvement booked in April when retail sales finally rose after months of steady decline, edging up 0.1 per cent over one month and reducing the fall over one year to 2.5 per cent.

Retailers also suffered a setback in the broader EU in May, as sales across the bloc's 27 nations fell 0.5 per cent over one month and 3.1 per cent over one year.