The Federation of Small Businesses fears that pressure on businesses to monitor who is a legal worker from the two nations, which join the EU next month, will be too much to bear.
Bulgarian and Romanian nationals will be allowed into the UK but government proposals aim to restrict the number allowed to work and businesses would be forced to check on who is and who is not a legal worker.
Allan Banks, policy spokesman for the FSBâ€™s North Buckinghamshire branch, said a number of local businesses already relied on the availability of East European labour and were obliged to check the validity of passports, birth certificates and national identity cards.
Mr Banks added: “To add another level of complexity will inevitably lead to confusion and errors.”
He urged the government to develop a simple and foolproof check system to verify potential recruits from Eastern Europe. “Government departments cannot and must not expect already over-stretched small businesses to do even more of their work for them,” Mr Banks said.