The arrested woman has been identified as Jenet Malsawmkimi, who hails from Mizoram.
"We got information that a northeastern woman was to come yesterday to the DDA Market in Vishal Enclave and laid a trap and arrested her," said a senior police officer.
Police said that Malsawmkimi and her Nigerian live-in partner, identified as one Oneka, resided in a rented accommodation at Rajouri Garden.
"She would supply drugs upon directions from Oneka, who is presently supposed to be in Nigeria. He is the mastermind behind this racket," the officer added.
Police recovered 6.5-kg of the drug from her possession with the haul estimated to be worth Rs 25 lakh on the international market.
According to police, Malsawmkimi would send drugs, namely crystal ephedrine, via cargo services to African countries after concealing the same inside automobile spare parts.
The accused, who studied up to Class 10th in Mizoram, came into contact with Oneka two years back and started living with him.
Police said that Oneka would procure a shaft propeller of a Maruti car from the automobile market at Kashmere Gate and then carve out its main piston to create a cavity.
He would then put the drug in a polythene bag and place it in the cavity in the shaft propeller before handing the same to Malsawmkimi to arrange for delivery through courier.