"The militants belong to Jammu and Kashmir, they are our children. We should not celebrate their killing," said Mr Mir, who represents the Watchi constituency in Kashmir's Shopian, one of the areas worst-hit by terror.
"Some of them are minors of age 14 who don't even know what they are doing. We should not glorify the killing of terrorists. It is our collective failure," said the lawmaker.
When reporters pressed him on whether he believed that the terrorists were "brothers and martyrs", as he had said in the House, Mr Mir replied, "Of course".
He added that he "also sympathized with the security forces and parents of soldiers who were killed."
Yesterday, he had said in the assembly that the government should hold talks with all parties concerned, including separatists, to resolve the Kashmir issue.
The lawmaker was himself a target just three months ago, when militants had thrown a grenade at his home. No one was injured.
Reminded of that attack, Mr Mir said: "That can be because of an ideological clash. We believe in India and they believe in something else, that is why I was attacked."
His comments were denounced by the BJP, which partners the PDP or People's Democratic Party in Kashmir.
"It is ridiculous, I condemn this statement. It is glorifying terrorism, you are playing with fire...Go and ask families of those who lost people to terror in the past 30 years. This is rubbing salt into the wounds of relatives of those killed in Pakistan-sponsored terror," said BJP leader and lawmaker Ravinder Raina.