One of the moderate voices in the Hurriyat, Lone was killed at a rally in Srinagar on Tuesday.
"This is the most condemnable act and it is time some action was taken to end once and for all Pakistan-supported terrorism in the valley," party spokesman V K Malhotra said.
He said the incident -- which came close on the heels of the May 14 attack in Kaluchak -- showed that "Pakistan would go to any extent in carrying out its terrorist acts".
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