The US Agriculture Department has reported that growing conditions for the US spring wheat crop were the worst in 18 years.

Flour company Odlums has warned consumers that the price of Irish bread is set to rise from next week because of poor wheat harvests and higher energy costs.

Odlums says world wheat stocks have slumped to a 25-year low, which will lead to increases of up to 20% in the price of flour from Monday. The company - owned by IAWS and Greencore - says this result in an increase of six cent on each loaf of bread, as well as increases in biscuits and cakes.

While it will be up to bakeries and retailers to decide on the bread prices, Odlums says it is 'inevitable' that the flour rise will be passed on to consumers.

Odlums says record summer temperatures have reduced crop yields across all markets, and prices of wheat on wholesale markets have jumped by between 20% and 40% over the past year. The company says the price increase is 'an essential reaction' to increases in its costs.

The demand for wheat for biofuels, in particular in the US is also a big factor.

July Report: Heatwaves and biofuel demand in Europe and US to fuel bread, pasta and beer price rises