Four suspected gang members have been arrested in Pakistan after allegedly tapping a teenage girl's spinal fluid to sell on the black market.

The men allegedly tapped the 17-year-old's spinal fluid, without her knowledge or approval, in the northern city of Hafizabad, around 35 miles north of Lahore.

Police believe the gang fooled the victim's father by pretending that they were carrying out medical research and would pay him if they could conduct a blood test on his daughter.

The father was offered a monthly fee that the gang allegedly said could go towards his daughter's dowry, Geo TV reported.

The alarm was raised when the girl returned home feeling weak and police were called and shown the building where the procedure took place, in the east of the city.

"It's one of the strangest cases of my career," Afzal Butt of the Hafizabad police department said according to the Guardian.

Police say they recovered a syringe and a bottle from the building and Dr Rehan Azhar, a medical superintendent at Hafizabad hospital, said an examination carried out by his staff found the injection was made for the purposes of spinal fluid removal.

Doctors can use spinal fluid in looking for conditions that affect the brain and or to help diagnose diseases such as cancer and meningitis.

Extracting the fluid can be dangerous and police believe that the gang may have been planning on selling the substance on the black market to 'hakeems' (traditional Islamic healers) or homeopaths.

"Gang members pretended to be from the DHQ hospital. The gang consists of three males and a female. We were informed by the victim's father of her sample being taken on the promise of a dowry package being provided under a government scheme," said SHO Hafizabad.

It was also reported that the victim may have been stripped naked for the procedure, which could mean further charges for the gang that could include sexual abuse, Butt said.