Defra's final report into the outbreak at a Bernard Matthews site in Suffolk concluded there was 'no specific proven source' although the 'most plausible explanation' was from imported meat from Hungary.
Defra said Bernard Matthews would receive the compensation for the healthy birds that were destroyed to prevent the disease from spreading.
However, the high level of compensation angered MPs after reports identified biosecurity breaches and hygiene lapses at the plant.
Leader of the Commons Jack Straw admitted he was “uncomfortable” with the payment.
Chris Huhne, the Liberal Democrats environment spokesman, said: “The failure to hold Bernard Matthews to account could be a dangerous precedent.”
Conservative environment spokesman Peter Ainsworth added: “Bearing in mind that there must have been a serious failure of bio-security at the Bernard Matthews plant, many people will be absolutely astonished that no one will be held responsible for the outbreak.”
Bernard Matthews said it always maintained biosecurity standards, and had taken steps to enhance measures.