The rise in price is said to have a knock-on effect on small bakeries

Flour prices are set to increase among the biggest bread makers, leading to a rise of two to four pence per loaf.

Rank Hovis, which owns eight mills and ADM Milling, which has nine, are both pushing up the price per tonne.

The UK's recent heatwave in the south east has been blamed for causing poor wheat harvests this year, coupled with the high costs of fuel among producers.

ADM Milling - which is pushing up flour prices by �28.75 per tonne - said its price hikes were an "essential reaction" to rising energy, fuel and wheat costs.

Rank Hovis is increasing its flour prices by an average �29 per tonne next month.

Small bakeries hit

The two companies together are the biggest millers in the UK.

ADM managing director Ian Pinner said: "This is the third year that we have had to accept increased energy costs which are now 30% higher than in November 2005.

"In addition global wheat markets have moved up sharply in reaction to supply and demand figures showing world stocks to be the lowest for 25 years."

Experts said this would mean price hikes of around 15% to 20% for major flour users.

The National Association of Master Bakers, which represents around 1,000 small UK bakeries, expects bread to go up by two to four pence per loaf.

Chief executive Gill Brooks said: "The small craft baker will be hit particularly hard."

Gordon Polson, director of the Federation of Bakers, told trade magazine The Grocer that bakers were also being directly affected by rising fuel costs.