Police and immigration officials raided a car wash in Rishton as part of an operation into 'modern day slavery'.
Officers say they found three Romanians being paid less than half the minimum wage and an Iranian refugee working illegally at Rishton Car Wash and Valeting Centre on Blackburn Road.
The four workers were being paid £30 a day for a 10-hour shift – or £3 an hour – which is less than the £6.50 minimum wage, a force official said.
No arrests have been made.
DC Andy Bleasdale said the swoop was part of Operation Eagle which aims to raise awareness with employers and employees about illegal working practices and aims to address concerns that people are working as modern day slaves in East Lancashire.
It involved police officers, tax and immigration officials staff from the Gangmasters Licensing Authority.
DC Bleasdale said: “The idea of the day was to go with partner agencies to identify people who maybe being employed in less than acceptable working conditions.
“When we spoke to the people at the car wash they said they were being paid £30 a day for a 10-hour shift. When we asked them if they wanted to make any complaint about their living and working arrangements they said they were happy.”
DC Bleasdale said the workers were being paid weekly and living at a nearby property on George Street.
He said: “The problem we have is in a lot of these cases people have left abject poverty in places like Romania to come here and work.
“What we would perhaps regard as poor and unsuitable living and working arrangements are a step up for them.
“We would think getting paid £3 an hour is poor considering what the minimum wage is but it is a significant improvement for them.”
DC Bleasdale said following the car wash visit they spoke to other businesses across East Lancashire which employ a ‘high number of Eastern European workers’.
He said: “There was no suggestion that any offences were committed by these companies but we wanted to try and raise awareness and let people know who we are.
“People might not realise it’s going on quite so close to where they live and maybe associate it with bygone eras.
“However with the influx of Eastern European workers into local communities people are sometimes finding themselves being taken advantage of, or not aware they are being taken advantage of.”
Operation Eagle is part of an ongoing operation into tackling and raising awareness of modern day slavery in Lancashire.
Lancashire Police define 'modern slavery' on their website as the movement of a person from one place to another into conditions of exploitation using deception or abuse of a person's vulnerability, even if the victim consents and is willing to be move.
Anyone with information is asked to call police on 101, the Salvation Army’s 24-hour confidential referral helpline on 0300 3038151 or visit www.lancashire.police.uk/help-advice/safer-communities/modern-slavery.