Acting on a tip off, the Special Task Force of city police made the seizure from Paikpara under Tala police station between midnight and 2 a.m.
"We have seized about 25 kilos of heroin. According to the grey market rates, the price range can be anything between Rs 75 crore and Rs 105 crore," Deputy Commissioner, Special Task Force, Pradeep Kumar Yadav told .
Two persons carrying the drug were arrested.
"One of them - Zuber - is from Bahraich in uttar Pradesh, the other person - Faizuddin - hails from Thoubal in Manipur. Both are known carriers for drugs," said Yadav.
Zuber was carrying around 20 kg of one type of heroin. Around five kilo of another type of heroin was found from Faizuddin.
"What we have gathered is they had brought the two drugs for exchange - one would take the other's variety to their customers. Then they will do their own mixing and processing and adulteration and concentration before selling it to their final customers.
"Because of the different qualities of the substance, customers ask for different things. So that's why they had exchanged it," he said.
The police also suspect they were negotiating about Yaba tablets, another narcotic drug.
"But we did not get any of those tablets from them," said the officer.
Zuber is the bigger carrier.
Cases under the Narcotic Drugs and Psychotropic Substances Act have been registered against the duo.
Heroin, an opioid drug manufactured from morphine, is found in the form of white or brown powder, or a black sticky substance known as black tar heroin. Other common names for heroin include big H, horse, hell dust, and smack, according to the US-based National Institute of Druge Abuse.
( With inputs from IANS )