Officials in the central anti-narcotics agency said Nigerian man has been identified as Augustin (33).
They said the two were apprehended yesterday after the Delhi zonal unit of the NCB first nabbed the woman, Tanzanian national Beatrice K Ndyetabula (40), from the Indira Gandhi International Airport in the national capital.
They said the woman landed in Delhi from Mumbai and when she was intercepted and frisked in the terminal area, 27 ribbon rolls concealing 4-kg of cocaine powder were recovered from her hand baggage.
She had arrived in Mumbai early yesterday from Kenya and the alleged drugs consignment was to be handed over to the Nigerian man in the national capital, they said.
The lady was purposefully allowed to hand over the consignment to the Nigerian man at a Delhi metro station, where he too was apprehended, they added.
"The 4-kg drugs consignment is suspected to be cocaine and is worth Rs 40 crore in the international market," a senior officer said.
"The two have been arrested under the provisions of the Narcotic Drugs and Psychotropic Substances Act (NDPS) and their links are being probed," NCB Zonal Director (Delhi) Madho Singh said.