The two reports published by government food safety bodies in response to the avian influenza at a Bernard Matthews farm provided few conclusions from officials as to what caused the outbreak.
Defra chief vet Fred Landeg warned: "We may never find the exact cause of the disease outbreak."
But the Defra report did outline a number of problems with biosecurity at the Suffolk site relating to animal by-products and in particular to waste trimmings held in bins outside the plants. Gulls, it said, were observed feeding on these trimmings and carrying them away from the processing plant into the area containing finishing units.
Other failures included polyethylene bags containing meat products and residual liquid being seen in uncovered bins with the potential to be blown across the site and holes being found in the sheds that could have allowed in birds and rodents.
In addition plastic covered bales of wood shavings used as bedding were kept outside, representing a potential means of introduction of infection.
The report also said that MHS records of enforcement activity, from January 2006 to date, recorded a number of instances where verbal advice to Bernard Matthews about deficiencies and non-compliance was given.
However, it was noted that in each case the problem was addressed and no further enforcement action was taken.
Alick Simmons, veterinary director of the FSA, said that the Bernard Matthews slaughterhouse had been re-licensed on 11 February after it have been shown to be totally compliant with EU law.
Defra's report concluded there was little evidence of wild birds spreading the disease to the UK. Landeg said additional surveillance had been carried out and a number of wild birds that had died in the vicinity of the Suffolk site had been examined and tests proved negative.
But he said: "We are not complacent and we are still making it a requirement for poultry keepers in the restricted zone to house their birds inside and be vigilant."
At the same time Landeg said importation of poultry products from Hungary was the most plausible route of transmission since virology showed that the H5N1 strain found in Suffolk was identical to that in Hungary.
However, he added that no imports of turkey meat had come from the restricted area in Hungary and he had a statement from the Hungarian chief vet on that. "If that had happened it would have been illegal."
Landeg said all avenues into the cause of the outbreak were being investigated and the investigation which would "continue to be open and all embracing."
The UK will form a triumvirate-working group with the EU and Hungary in relation to technical issues. "Once the Hungarian experts have had a chance to read this report we will discuss," Landeg said.