Acting on a tip off, the customs officials were keeping surveillance on the two foreign nationals, who had arrived here about 3-4 days back.
The duo, who arrived here on Wednesday to board a flight to Johannesburg via Nairobi, were intercepted.
"On examination of their baggage, it was found containing white powdery substance, which weighed 60.180 kgs. The recovered substance in the form of powdery substance was tested by the customs officer and it was found positive for Methaqualone, a controlled substance under Narcotic Drugs and Psychotropic Substances (NDPS) Act," a customs official said.
The international market value of the seized substance is over Rs 48 crore, he said. A kilogram of Methaqualone fetches around Rs 80 lakh in the open market.
"The accused were being interrogated about the consignment and their associates," the official said while refusing to divulge their identities.
Methaqualone is a sedative and a hypnotic drug which is commonly used in rave parties. It is also one of the main constituents of party drug Mandrax.