Immigration officers arrested four men at a builders and timber merchants in Southall last week.
Officers from the UK Border Agency descended on Western Timber and Builders Merchant in Southall and arrested three employees and a customer.
One man was arrested for entering the country illegally, two are believed to be failed asylum seekers and the fourth was arrested for “immigration offences”.
Western Timber and Builders Merchant must now prove that they did the correct checks on their staff, or they could face fines of up to £10,000 per illegal worker.
Salma Raja, head of the UK Border Agency’s Ealing Local Immigration Team, told the Ealing Gazette: “Those who employ illegal workers are not only breaking the law, they’re also taking jobs from those who do have the right to work and undercutting legitimate businesses and traders.”
Merchants can check what steps they need to undertake to avoid employing illegal workers via the UK Border Agency’s Employers Helpline on 0300 123 4699.