More than 100 kilos of the drug were recovered from an address in Old Swan, Liverpool, on Wednesday as part of a probe into county lines dealing.
A 53-year-old woman has been arrested and held on suspicion of possession with intent to supply class A drugs and is being questioned at a local police station.
Detective Inspector Gary Stratton, of Merseyside Police, said: “This property was used to conceal over 100 kilos of cocaine worth around £10 million.
“This is the second seizure of class A drugs in Merseyside this week.
“Yesterday a seizure of 38 kilos of cocaine was seized with a street value of £2.6 million.
“Organised crime is hugely damaging to our communities, often involving intimidation, violence and creating fear.
“Those who are involved in organised crime have no thought for anyone other than themselves, and their criminal intent and greed.
“Project Medusa is dedicated in removing any illicit drugs from our communities and taking those who store them off our streets.
“By working with partners we can disrupt county lines gangs and help vulnerable members of our community who may be exploited by these criminals.”
In a separate police operation, an estimated 38kg of suspected cocaine was found within shopping bags in a van in Roby on Tuesday.
Merseyside Police say officers stopped and searched a grey Volkswagen van on Bridge Road and discovered five large shopping bags filled with blocks of white powder in the rear of the vehicle, believed to be cocaine.
A 40-year-old man from Huyton was arrested on suspicion of possession with intent to supply a controlled Class A drug, cocaine, concerned in the supply of a Class A drug, cocaine and acquire use/possess criminal property.
A force spokesperson said: “Project Medusa officers lead the force’s daily response to County Lines activity, working to intercept weapons, drugs, and illicit cash, while identifying and safeguarding individuals vulnerable to exploitation by organised crime groups.”
