Acting on a tip-off, a team of Customs officials reached the courier company in Andheri (East) at about 12.30 am today and opened the consignment, on which the cover read as "Food articles", the official told PTI.
Methaqualone drug weighing 50 kilograms was found in the consignment that came from Delhi yesterday, the official added.
"It is the biggest seizure in the recent past. The person who sent the consignment to Mumbai is yet to be identified and traced," the official said.
The accused planned to smuggle the drugs to the UK on a Qatar flight at 4.30 am today, the official said.