"I am extremely sad to learn about the terror attack of yesterday in which a number of army personnel lost their lives and several were injured in Manipur's Chandel district.
"Such random attacks on security forces performing their duty must be put down with a firm hand. I call upon all authorities concerned to work in close concert to bring the perpetrators of this heinous attack to justice and to maintain law and order in the state of Manipur," the President said in his message to Army chief General Dalbir Singh.
"I am sure all possible aid is being provided to the bereaved families and medical assistance to the injured.
"Please convey my condolences to the families of the deceased personnel. I pray to the Almighty to give them the strength and fortitude to bear this irreparable loss. I also wish speedy recovery to the injured persons," the President said.
In the worst such attack in two decades, insurgents had yesterday ambushed a military convoy in Manipur's Chandel district, killing at least 18 army personnel and injuring 11 others.