The two pest controllers who died at Banham Poultry in Attleborough worked for Ecolab Pest Elimination.
Emergency services were called to the factory on Station Road at about 1.10am on Thursday, October 4, following reports two subcontractors from a pest control company working on the site had been found dead.
Police and the Health and Safety Executive have launched a joint investigation and are looking into a refrigeration gas leak in an effort to determine whether it has any link with the men's deaths.
A police spokesman confirmed on Monday that the two men had not yet been formally identified and that investigators were waiting for the results of post-mortem examinations.
The identities of the men are expected to be made public later this week.
But the British Pest Control Association (BPCA) has confirmed that the pair worked for Ecolab Pest Elimination division, which is based in Cheshire.
Ian Andrew, chief executive of BPCA, said: 'The BPCA community is devastated by this news. Our thoughts are with the families, colleagues and all those affected at this difficult time.'
Ecolab is carrying out its own investigation and a spokesman said: 'Our thoughts are with their families at what is a difficult time.'
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