Also read: Day 4 live updates on Nepal earthquake
Speaking to news agency Reuters, Koirala said: "The government is doing all it can for rescue and relief on a war footing. It is a challenge and a very difficult hour for Nepal."
The death toll as of Tuesday reached 4,349. Koirala ordered his government to coordinate the relief work. He is likely to address the nation later on Tuesday.
Meanwhile, Union Home Minister Rajnath Singh said that the Indian forces were doing a remarkable job in Nepal with respect to the relief and rescue operations. NDRF team carried out relief operations at New Bus Park in Kathmandu.
India had immediately rushed to Nepal's aid after the deadly 7.9 magnitude earthquake struck the nation. The aftershocks continued even on Tuesday morning when Nepal experienced mild tremors.
Crisis loomed over quake-hit Nepal with an acute shortage of food, water, electricity and medicines as fear of another quake kept tens of thousands of people out in the open.