Rescue teams identify bodies dug out of the collapsed Sitapyla church in Kathmandu, Nepal. Image Credit: AP

Kathmandu: The number of people killed in Nepal by the Himalayan country's worst earthquake in eight decades has risen to 3,726, a home ministry official said on Monday.

That number represented a jump of 500 from earlier on Monday. Some in the government fear the toll from Saturday's 7.9 magnitude quake could rise to as much as 5,000.

Nearly a million children have been "severely affected" by the quake, a spokesman for the United Nations Children's Fund (UNICEF) said, as rescue and aid workers struggle to cope.

With hundreds of thousands of Nepalis sleeping out in tents or in the open, UNICEF said its relief workers were watching for waterborne and infectious diseases.

"What we know that at this point is there are nearly a million children who are severely affected. Our biggest concern for them right now is going to be access to clean water and sanitation, we know that water and food is running out," UNICEF's Christopher Tidey said by telephone.