According to sources in the CBI, the MHA asked the agency to investigate the issue after the Border Security Force submitted a report to it describing the prevailing situation.
In West Bengal's North 24 Parganas district's Kajuli, seven smugglers were arrested and six heads of cattle seized.
Interrogation by the state police personnel, who were handed over three cattle smugglers last month in Malda, also revealed the IEDs were procured from Murshidabad district.
Following an SC order, the force has been left scratching its heads to what to do with the recovered cattle
Few such cattle, with an IED placed inside a small aluminium canister tied around their neck, were recovered from the river near the Harudanga border post along the south Bengal frontier.
With Bakri-Eid approaching, smugglers are getting desperate and attacking BSF jawans on being challenged
The troops have been asked to maintain an "aggressive posture" and ensure that the crime of cattle smuggling is effectively checked.
Altogether 159 cows, which were kept in a cattle shelter at Devipur in Sipahijala district, have died since May 14 last.