The accused, who is in her early thirties, had arrived at the IGIA to board a flight to Nairobi on Saturday.
She was intercepted at the boarding gate by customs officials and allegedly found carrying 15 kgs of Methaqualone in her baggage, said Neeta Lall Butalia, Commissioner of Customs (Import and General).
Methaqualone is a kind of sedative used for medical purposes. However, it is commonly used as party drug.
A kilogram of Methaqualone fetches Rs 80 lakh in black market. "The international market value of the seized goods is Rs 12 crore approximately," she said.
The passenger has been arrested and remanded in judicial custody, the official said.
Earlier on Wednesday, another South African woman was arrested at the airport for allegedly trying to smuggle 22.235 kg of Methaqualone worth about Rs 18 crore out of the country.
She was to board a flight to Johannesburg via Addis Ababa.
