"Just five minutes before the earthquake, I was with the PM. When I came home, called me and said he had called a meeting on a very major disaster. I have no problem in admitting that the alertness that I should have shown as home minister was shown by the PM," Mr Singh said in a statement in the Lok Sabha on the disaster that has left over 3,700 dead.
The government has decided to grant visas on priority to foreigners who want to come to India be evacuated from Nepal, said the home minister.
He said PM Modi spoke with about a dozen state chief ministers immediately after the earthquake. "We decided that states bordering Nepal should send buses to evacuate Indians," Mr Singh said.
"People in both Nepal and India who have been affected will be helped by our government." he added.
The Indian Air Force has evacuated over 1,900 citizens from Nepal in about a dozen sorties. More sorties have been planned for today; aftershock and poor weather had hampered some flights.
A team of Indian officials from various ministries has gone to Nepal to coordinate relief and rescue operations.