Firebrand BJP MP Yogi Adityanath and some others have received a "threatening letter" allegedly from 'Jaish-e-Mohammad' terror outfit, police said on Sunday.
The letter, addressed to the Director General of Police, was received on Friday and was sent through speed post by one Mujahideen Siddiqui, who identified himself as an active member of 'Jaish-e-Mohammad', they said.
Though police traced the address on the envelope, it was found to be fake, they said, adding further investigation is on.
"Security for Yogi Adityanath and the famous Gorakhnath Temple here has been tightened following the threat," Deputy Inspector General (DIG) Aseem Arun said.
Similar threatening letters were also received by local BJP MP Radha Mohan Das Agrawal, Archana Tomar (advocate, Lucknow), Sureshwar Singh (MLA, Mahsi, Bahraich), Prakash Verma (Bajrang Dal, Kanpur) and Divya Giri (Lucknow), sources said.
Meanwhile, Adityanath said he would not bow down to such threats and would continue to work for "national integration".