Hovis is to break its pledge to use only British wheat in its loaves after last year's severe wet weather hit harvests.
The Premier Foods-owned group will start using additional grain from the European Union this weekend and is expecting to reduce its British wheat-buying by around a third over the year ahead after farmers saw the worst harvest for 35 years.
Hovis introduced its 100% British wheat pledge in 2010 and has been a vocal supporter of UK producers, using 450 farmers to grow premium "red" wheat exclusively for the group.
But Premier said the poor harvest in 2012 and concerns for this year's crops after the recent flooding left it with "no option".
It said: "With the 2012 UK wheat harvest being the worst for more than 35 years, we are finding it increasingly difficult to maintain the high quality bread standards we require.
"Therefore, we have been put in a challenging position and have had no option other than to use a percentage of imported wheat from the EU."
Premier added that the heavy rain and flooding in recent weeks has also meant that UK farmers are 15% to 20% behind with sowing for their next crops.
The group will introduce a percentage of EU wheat on a small number of Hovis lines over the next week, which will see the pledge to use only 100% British wheat removed from those packs, with the rest of the range set to follow by the end of the month.
Hovis will continue to use only British wheat on its Farmers Loaf range, which was launched last April to champion British grain amid a £3.5 million marketing campaign.
Premier Foods said it remained committed to British wheat, but made the decision based on ensuring the best taste and quality of its loaves.