Ranjit Kumar, aged 36, was jailed for 12 months for using a fake identity to secure a job. The illegal worker had been working at a clothing factory in Leicester.
The Indian national was caught after routine Covid-19 checks were made.
Kumar had visa applications to visit the UK rejected four times but he entered Britain illegally and used a fake ID document to secure a job in a false name.
Officials made a routine check at Singh Clothing Ltd, in Brighton Road, on July 3, 2020, to check the factory was operating in a Covid-19 compliant way.
The prosecutor Elizabeth Dodds said Kumar was stopped by an officer who saw him using a fire exit in order to avoid them. He appeared nervous when questioned.
Kumar produced a Portuguese ID card with his photograph, but in the name of someone else who had genuinely been issued with a visa