According to informed sources, the central government is concerned that these killings may derail the peace process in the state.
On April 21, former PREPAK Chairman Ningombam Nabachandra and his driver were shot dead in their 'safe house' inside the camp of 7 Manipur Rifles in Imphal East district. The killers escaped unnoticed.
Some other former insurgents also had been gunned down in separate incidents in the state.
With such killings on the rise, at least one militant outfit in Imphal West district has taken up arms once again, even though it had suspended operations.
Police sources said the development has vindicated those militant groups that did not suspend their operations.
The peace process in Manipur began in May 2000 when the army reached an agreement on suspension of operations with some tribal outfits. However, the state government remained non-committal, observers here pointed out.
Chief Minister Okram Ibobi Singh, who also held the home portfolio then, told IANS that his government was not taken into confidence over the suspension of operations.
Despite the agreement, police and paramilitary forces continued to arrest and kill some of the former insurgents. It was then that the Union home ministry stepped in.
Eventually, another agreement was signed in August 2008 -- this time taking the Manipur government into confidence. "Fifteen tribal and three non-tribal underground organisations joined the national mainstream after signing the agreement. They have been placed at different designated camps since then," an official told IANS.
But some leaders of these outfits are not happy because of the meagre stipend they get. Moreover, no political dialogue has been initiated for a settlement. The former insurgents, who have been disarmed, are also in constant fear of being killed.
Villagers have been protesting the government plan to set up designated camps for former militants in the close vicinity.
Referring to reports of some inmates indulging in unlawful activities, Manipur Home Minister Gaikhangam said: "The government shall come down heavily if the inmates violate the ground rules of the suspension of operations".
Police had arrested some inmates on the charge that they were involved in extortion bids.