India's coronavirus infections surged past 5 million on Wednesday, piling pressure on hospitals grappling with unreliable supplies of oxygen that they need to treat tens of thousands of critical patients.

In the big states of Maharashtra, Gujarat and Uttar Pradesh, that are also some of the worst-affected by the virus, demand for oxygen has more than tripled, doctors and government officials said, prompting urgent calls for help.

"Desperate patients have been calling me through the night but I don't know when I will get stock," Rishikhesh Patil, an oxygen supplier in the western city of Nashik, told Reuters.

Reuters