Two men were arrested in Paikpara early on Tuesday with 25kg heroin worth more than Rs 100 crore, police said.

Officers of the city police’s special task force claimed it was the biggest heroin haul by any agency in Bengal and the Northeast in at least five years.

Two varieties of the drug were found on the two. Moulana Faiyazuddin, 49, who hails from Manipur’s Thoubal district, had 5kg of the white variety, while Juber, 40, from Uttar Pradesh’s Bahraich district, had 20kg of the violet variety, an STF officer said.

It seems the two were in Calcutta to mix the two varieties with other substances to form other drugs that are in high demand in Calcutta and adjoining areas and in the Northeast, the officer said.

It is unclear how the two got to know each other but they were in touch, the police said.

“We believe both used to mix two varieties of the drug to sell to their fixed clients,” an investigating officer said. “It could be that the two chose Calcutta because their clients might have links with international drug peddlers.”

The drug was found in small plastic packets inside plastic sacks, another officer said. Neither of the two resisted when officers in plain clothes stopped them to check the sacks, he said.

The Bankshall court sent the two to police custody till February 4.

“We will find out more about the drugs and the supply chain once we get to interrogate the two,” the officer said.