Guwahati, October 7 : Assam Police have seized narcotic substances worth Rs. 3.5 crore in Karimganj district and arrested three persons in connection, a senior officer said on Saturday. Karimganj SP Partha Pratim Das told IANS: 'Based on a tip-off, we carried out a drive in Ratabari area adjacent to the Mizoram border on Friday night. We stopped a vehicle coming from Mizoram in which narcotic substances were kept hidden in several soap boxes.' The police recovered at least 563 grams of heroin from 52 soap boxes. The arrested persons have been identified as Giyas Uddin, Numan Uddin and Abu Bakkar. Among them, Giyas Uddin is a native of Tripura, while the two others are from Karimganj district. Police have been interrogated the trio to unearth further links in the interstate drug trafficking. Further investigation is underway. /IANS