Hussain added that the proposal had been turned down "due to military and security reasons". The Union Ministry of Environment and Forests had earlier cleared the proposal.
"We have received a letter from the Defence Ministry today informing us that the proposal had been turned down. However, we have requested the ministry to review the decision," said Hussain.
The proposal of using drones for aerial surveillance of the park was mooted in 2012 when the park registered a sudden spate in poaching of one-horned rhinos.
Union Minister of Environment and Forest Jayanti Natarajan, who visited the park last year, said she would approach the central government for sanctioning a drone for better aerial surveillance of the park.
0ver 20 rhinos were killed by poachers in Assam last year and 18 of them were killed in the Kaziranga National Park so far this year.
Hussain said two more rhino carcasses were recovered from near the national park Wednesday morning.
"The carcasses were spotted by a forest patrol in Burhapahar range of the park. Preliminary investigation indicated that militants were behind the killing," said Hussain, and added that investigations were on to trace the culprits.
Hussain said the department was proposing to fence a stretch of 50 km in the Kaziranga National Park with solar powered electric fencing to stop rhinos from straying outside.
"Wildlife experts normally suggest that the free movement of wildlife should not be obstructed. However, we are planning to erect removable fencing in certain areas through which the rhinos stray outside the park and fall prey to poachers," he said.
"We will select locations after consultations with experts and wildlife NGOs who are working in Kaziranga for conservation," he said.
The minister also said that the centre had sanctioned additional firepower for the Assam forest department and the state government would now buy 2,000 self-loading rifles (SLR), 540 carbines, 30 nine mm pistols, 25 revolvers and 10 light machine guns (LMG) to equip the forest department.
--IANS (Posted on 21-08-2013)