A government order to ban cow slaughter and illegal transport of milch animals was passed during the previous Akhilesh Yadav government in the state but was never strictly implemented.
"NSA and Gangsters Act is to be invoked against those involved in cow slaughter and trafficking of milch animals for slaughter," the DGP's orders said.
Under NSA, the government can detain a person for as long as it wishes and the authorities need not disclose the grounds of detention.
A person booked under the provision of Gangsters Act becomes part of a gang listed in police records. It entitles the police to keep track of those booked under the Act and issue summons to them for attendance at the local police station for questioning even if no fresh case is lodged against them.
The Act permits the police to seek remand of an accused for a maximum of 60 days as compared to a maximum of 14 days under normal circumstances.
The DGP also directed Senior Superintendent of Police (SSP) and Superintendent of Police (SP) of all districts to "effectively control" illegal activities committed by "vigilantes" in the name of cow protection, morality, religious conversion or illegal trafficking of milch animals.
Mr Singh asked the officers to register FIRs against vigilantes when they violate the law and to prepare dossiers on them after identification with the help of intelligence networks. "These people / organisations should be informed that they do not have a right to act illegally by taking the law into their hands," he said.
The directive comes against the backdrop of incidents in which 'gau rakshaks' or such organisations reach a spot where an alleged cattle slaughter has taken place and cause traffic jams, assault people and indulge in arson. Similar incidents have been reported about the illegal trafficking of milch animals in which 'gau rakshaks' damage vehicles and assault the driver.
The order comes amid a raging heated debate on the centre's notification which bans the sale of cattle for slaughter in market places. The notification has triggered protests from various quarters, including the Kerala government and certain BJP leaders in Meghalaya.
The Madras High Court had on May 30 stayed the notification for four weeks. Kerala Chief Minister Pinarayi Vijayan had last week written against the notification to Prime Minister Narendra Modi.
He had also written a letter to counterparts in other states, including Uttar Pradesh Chief Minister Yogi Adityanath, saying the notification was "nothing but a covert attempt to usurp the powers of the state legislature".
Union Environment Minister Harsh Vardhan has said the centre may consider any vital proposal on the new law on cattle trade and slaughter.
The centre's new notification has imposed a blanket prohibition on the slaughtering of cattle (cows, bulls, buffaloes, camels, heifers) brought from animal markets. The notification bans the sale of cattle for culling and also restrains sacrificing the animals for religious purposes.
The MoEF notified the stringent Prevention of Cruelty to Animals (Regulation of Livestock Markets) Rules, 2017 under the Prevention of Cruelty to Animals Act, 1960, on May 25, banning the sale and purchase of cattle from animal markets for slaughter.
In Uttar Pradesh, the centre's decision had elicited a positive response from organisations running cow shelters, which termed it as an "appropriate step" in the "right direction."