Junior doctors and interns in state-run hospitals have been on strike for nearly a week in protest at a government affirmative action programme aimed at increasing the number of seats for poor and lower-caste students in India's universities.
The industrial action began last Sunday and has crippled hospital services.
The focus in the capital is the state-run All India Institute of Medical Sciences, the hospital where nearly 100 students from five medical colleges began a hunger strike on Sunday.
Their numbers dropped to 35 on Thursday, as many fell sick and temperatures rose to 40C.
Arnab Pal, a spokesman for the Resident Doctors Association, said that doctors also set fire to a pile of notices served by the health ministry on Wednesday that threatened dismissals if they did not resume work within 24 hours.
Poor Indians are those most affected by the action, with many having to seek treatment in expensive private facilities while the strike is on.
Big crowds sought medical help outside strike-hit hospitals in the northern state of Punjab, Gujarat and Maharashtra in the west and Orissa state in the east.
In Kolkata, Joyshree Mitra Ghosh, director of the West Bengal Medical Association, said students were staying away from classes and doctors were not tending to patients.
"We will keep up our protests indefinitely till the government concedes our demands and rejects reservation completely"
Doctors are angry at government plans to increase quotas for lower caste students in state-funded medical, engineering and other professional colleges from 22.5% to 49.5%.
They rejected any dialogue with cabinet ministers on Thursday, a day after the government named a panel of three ministers to examine the government plans.
"We do not want talks with any ministers. We want to speak to the prime minister and Sonia Gandhi," said Subroto Mandal, a protest leader and junior doctor in New Delhi.
Gandhi is the head of the Congress party.
"The ministers are in no position to give us any definite assurances. We will keep up our protests indefinitely till the government concedes to our demands."
Opponents of the plan say higher quotas will hurt professional standards.
Medical students say reservation
quotas will hurt standards
Aniruddh Bhatia, a student doctor, demanded the setting up of a government panel "to examine how far existing reservations have helped".
"We have had reservations for several decades now. The government should assess how reservations have so far helped India's economically and socially backward before new quotas are added," he said.
Applicants compete fiercely for entrance into India's elite medical and technical schools.
Despite anti-discrimination laws, India's lower castes, comprising about 80% of the population, are still at the bottom in social areas such as education, income, employment, asset ownership and debt.