The Amritsar Rural police have busted two illegal arms and narcotics supply networks, arrested four persons and recovered a sophisticated M16 rifle, nine illegal pistols, 25 live cartridges and 15 kg of opium during separate operations.The recovery of sophisticated weapons, including an M16 rifle of military design, has raised concern among police circles over the illegal circulation of such firearms.DGP Gaurav Yadav said the police were investigating the source of the weapons and the suspected narcotics supply chain.According to the preliminary probe, the accused are allegedly linked to foreign-based smugglers and were involved in procuring illegal weapons and narcotics from Pakistan with the help of drones on a large scale, the police said.Separate FIRs have been registered at the Gharinda and Lopoke police stations.IG, Border Range, Gurpreet Singh Bhullar said further investigation was underway to establish the backward and forward linkages of the networks and ascertain the extent of the alleged illegal arms and narcotics trade.