The heroin was distributed in Punjab, Delhi, and other states.
Four people, including an Afghan national, were arrested with over 21kg heroin worth Rs 130 crore in their possession, police said on Friday.
The accused have been identified as Parvej Alam, Naseem Barkazy, Shami Kumar, and Rajat Gupta, they said.
Police arrested Barkazy, an Afghan, from Karkardooma on a tip-off, and found 3kg of fine-quality heroin on him, Deputy Commissioner of Police (Crime) K P S Malhotra said.
When interrogated, Barkazy revealed he was part of an international drug syndicate and operated at the behest of his associates based in Afghanistan, he said.
He also revealed that an associate of his, Alam, helps him in manufacturing and mixing of heroin.
Alam had a large quantity of heroin on him, he told police, the DCP said.
On the basis of the information, police raided a place in north east Delhi's Bhajanpura area, seizing 7.4kg heroin and Rs 1.25 lakh cash from Alam's possession, police said.
When they dug deeper, police found that the nexus was spread across the country with deep roots in Punjab.
One of their associates, Kumar, was found to have recently received a consignment of heroin for distribution in Punjab, police said.
Raids were then conducted in Mahavir Nagar and Dabri to apprehend Kumar, they said.
During the raid, another 11kg of heroin and precursor (mixing chemicals), and Rs 22 lakh in cash were recovered from his possession, and Kumar was arrested, police said.
In his turn, Kumar said he was acting on behalf of one Pankaj and all drug proceeds were being managed by Rajat Gupta, who has also been arrested.
It was revealed that the accused were members of an international syndicate with Afghanistan as their major source of supply, with swathes of its land sown with opium, police said.
The accused used to communicate with each other through WhatsApp and other voice over internet protocol (VOIP) applications.
Opium, in liquid form, was trafficked via air and sea routes and was received by Barkazy, police said.
Alam was found to be one of the main parts of the syndicate as he was in charge of processing the liquid opium into powder form.
This powdered heroin was then distributed in Punjab, Delhi, and other states through their couriers and distributors spread across the country, police said.
Alam was previously arrested under the NDPS Act and during his jail time, he came in touch with some Afghan nationals and started working with them, they added.
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