Officers carried out dawn raids at addresses in Preston and Blackburn on Wednesday and arrested four people on suspicion of human trafficking.
Police say that following consultation with the Crown Prosecution Service two men have now been charged.
Andrei Vitan, 23, of Andrew Street, Preston is charged with human trafficking and controlling prostitution and Nicolae Constantin, 23, of Palatine Road, Blackburn, has been charged with human trafficking, controlling prostitution and indecent exposure.
They were both due to appear before Blackburn Magistrates’ Court today.
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Two other men aged 37 and 38 from Blackburn have been released under investigation.
Lancashire Police's East Exploitation Team began Operation Elco earlier this year looking into the activities of a trafficking ring operating in Preston and Blackburn.
A spokesman said: "The investigation began to show the group were operating and controlling the prostitution of women across different parts of the county and more widely.
"Prostitution services and brothels were uncovered in Blackpool, Warrington, Norfolk and Leicester that were being controlled by the group.
"Lancashire Constabulary is committed to investigating human trafficking and modern slavery and taking robust action against those willing to exploit others for financial gain."
Anyone with any information can contact the independent charity Crimestoppers on 0800 555 111 or complete an anonymous form online www.crimestoppers-uk.org . When you contact them your identity will be protected.
If you think that someone is in immediate danger call 999, if you suspect slavery is happening and there is no immediate threat to life then contact us on 101.
Lancashire Victims Services are also here to offer help and support, even if you haven’t reported a crime to the police. Contact them on 0300 323 0085.
There is also a national Modern Slavery Helpline offering confidential help and advice, you can also report information to them on 08000 121 700.
For more information see our website https://lancashire.police.uk/help-advice/safer-communities/modern-slavery/