A suspected Birmingham brothel made £13m in three years by attracting as many as 200 customers a day.
Libra Club, in Summerhill Road, had 20 women working there at any one time and is suspected of being used as a front to launder proceeds.
Up to 50 officers raided the premises in an early morning operation on Tuesday (10 February) following months of surveillance by West Midlands Police.
Simultaneous warrants were also executed at sister venue the Sunset Club − a licensed lap-dancing bar in the city centre − and the homes of club bosses in Edgbaston, Kings Heath and Hall Green.
A woman aged 29 and a 24-year-old man were arrested from the Libra Club and Sunset Club respectively, on suspicion of managing a brothel, while a 25-year-old woman was also arrested from the Sunset Club on suspicion of money laundering.
Three more women, aged 47, 54 and 63, plus a 64-year-old man were arrested during the other house raids and around £50,000 in cash was seized. All of those arrested remain in police custody.
Police were tipped off by local residents who grew concerned after violence at the club.
Sergeant Tony Smith said: "It's suspected the Libra Club has been operating as a highly-profitable brothel − making upwards of £13m in the three years it's been open − with up to 20 women working there at any one time and attracting 200 customers a day.
"This morning's raid was months in the planning and is in response to concerns from local residents and a series of series incidents there including a shotgun discharge, an arson attack and several violent disorders.
"Brothels are often linked to wider criminality like money laundering and other organised crime... and as this operation shows we will take decisive action against suspected illegal venues."