Associated British Foods warned that lower European Union prices would hit profit in its sugar business, sending shares in the owner of the Primark fashion chain sharply lower today. 

AB Foods stuck to its overall forecast for "progress" in adjusted operating profit and adjusted earnings per share (EPS) for the year to September 2018.

It said the sugar weakness would be offset by higher margins at Primark, which accounts for about half of its revenue and profit. Primark trades as Penneys here.

Shares in AB Foods, which also owns major grocery, agriculture and ingredients businesses, fell as much as 5.7%, the biggest faller on Britain's FTSE 100 index. 

Revenue at its AB Sugar business, which contributed about 16% of group profit last year, fell 17% in the third quarter to June 23, which the group said was entirely the result of much lower EU prices hitting its UK and Spanish businesses. 

It had warned on sugar profits in January. 

EU sugar prices were continuing to fall, driven by low world sugar prices and excess supply following very high sugar production in the EU last year, it said. 

For the group's next financial year (2018-19) this level of EU sugar prices would represent a substantial reduction compared to those achieved this year, AB Foods said. 

"As a result, our expectations for sales and profit at AB Sugar, both for this financial year and next, are lower than previously expected," it warned. 

Analysts had on average been forecasting group adjusted operating profit of £1.4 billion and adjusted EPS of 134.4 pence for 2017-18, Reuters data showed, up from £1.36 billion and 127.1 pence made in 2016-17. 

Finance director John Bason declined to say what impact the warning on 2018-19 sugar profit would have on the overall group outcome for that year. 

Third quarter sales at Primark were 6% ahead of last year on a constant currency basis, with like-for-like sales showing improvement from the first half outcome. 

"We've really got the fashions, we've got the best prices around," said Bason. 

"Rather than having to shop, people want to shop in Primark stores and when the weather's been good we've seen big increases in like-for-likes (sales)," he said. 

Primark's second half operating margin was forecast to be "well ahead" of last year, thanks to better buying terms and the beneficial effect of a weaker US dollar. 

The fashion retailer sources the majority of its goods in dollars from the Far East.