The £400m-a-year Bernard Matthews poultry empire was in disarray last night as British and Hungarian government inspectors studied the movements of birds and people on and off its farms, MPs accused the firm of telling "untruths", and sales of poultry slid.

For days, the company has maintained that operations in Hungary and Suffolk are entirely separate with no trade between them but yesterday, as the bird flu crisis threatened to engulf the firm, it admitted that not only was there significant trade between the plants, but that it could have imported infected turkey meat.

"We do transport meat but we don't move live birds between Hungary and the UK," said commercial director, Bart Dalla Mura. "It is possible [that we imported infected meat] but our paperwork is absolutely clear that the materials we have imported are from outside the exclusion zone. Our checks say that we have not imported anything from that area.

"If we had any concerns about our Hungarian operation we would say so. We operate with as much rigour in Hungary as we do in the UK," he added.

Mr Dalla Mura also revealed that workers at the Holton plant had been processing meat from Hungary this week. "They were working with some UK and some Hungarian meat," he told the Guardian. "We've taken a couple of loads from Hungary this week." Asked why the company had failed to share information about its operations in Hungary after the Guardian's disclosure on Monday that there was a possible link, Mr Dalla Mura said: "There's a very good reason for that. I was told by the state vets that they wouldn't investigate [the Hungarian link] because it was so improbable. But then they decided to be more thorough in their investigation."

The government said it was broadly satisfied with the company's explanations and that it did not appear to have broken the law, but opposition MPs leapt on the changing versions of events.

"Their claim that there were no links between Hungary and Suffolk has been exploded," said Lib Dem environment spokesman, Chris Huhne. "There appear to have been serious bio-security lapses. If proved, this suggests irresponsible behaviour which disregarded public health." The Tory shadow environment secretary, Peter Ainsworth, said: "The company is in deepest trouble. It has not been completely clear with Defra or the public."

Amid signs of a consumer backlash, Bernard Matthews has engaged crisis management specialists to handle its PR and issued a statement saying that all its products are "perfectly safe to eat".

But Green MEP Caroline Lucas called for an EU-wide moratorium on the international trade in poultry. "The untruths that the company have told the public and the government call into question everything else it says," she said.

The company was also accused of hiding the fact that it imports large numbers of poultry and legally labels them British. Last week it said all Bernard Matthews' birds were "home grown".

It emerged that the company was legally importing meat from Latin America and also possibly Turkey, where an outbreak of avian flu was announced yesterday. One source in the Suffolk factory said: "They are definitely coming in from Brazil."

There was also increasing disquiet in East Anglia that the turkey tycoon, who employs 5,000 people and whose personal wealth is thought to be more than £300m, has still not visited the farm.

An employee from a farm outside Norwich said: "We have been told nothing, except not to talk to anyone about what is going on. He should come out of hiding."