Gugu Myeni and AFP

Nigerian police rescued pregnant women after raiding an illegal orphanage thought to be a "baby factory", a spokesperson said on Friday.

Young women between the ages of 18 and 20 thought to have been at the orphanage against their will in order with intention for them to bear children to be sold.

"We discovered the baby factory in Uruah local government area of the state during a raid following a tip-off," assistant police superintendent Oyekachi Orji said.

seven women were freed from the orphanage but no babies were discovered.

The suspected owners of the "baby factory," which include a hsuband and wife and an accomplice, have been arrested.

"The suspects usually lure young girls to get pregnant with a promise of 70,000 naira (340 euros, $445) after having their babies, which they sell to ritualists," he said.

According to AFP a number of these "factories" have been discovered across Nigeria, often intending to sell children to childless couples.