Kingsmill and Silver Spoon maker Associated British Foods has reported a rise in group revenues for the past six months but warned sugar production costs would weigh on profitability in the second half.

Group sales were up 9% to £5.21bn in the 24 weeks to 5 March, while pre-tax profits slipped slightly to £319m.

Increased volumes and market share for Kingsmill helped grow grocery sales by 8% to £1.73bn, with profits up 17% to £111m. But margins came under pressure from the continued increase in wheat costs.