Junior doctors agitating over the rape and murder of their colleague at the RG Kar hospital continued their fast unto death for the sixth day on Friday, even as the condition of one of the medics on hunger strike, who was hospitalised, remained "critical", health officials said.

Aniket Mahato was admitted to the state-run RG Kar Medical College and Hospital on Thursday night after his health condition deteriorated due to continuous fasting since Sunday.

A five-member medical board was constituted to oversee the treatment of Mahato, the health officials said.

"He was brought to the hospital in an unconscious condition. His condition is critical. He has been provided with oxygen and other necessary treatment for a patient who has not consumed water for the past few days. His condition is quite unstable," Dr (Prof) Soma Mukhopadhyay, CCU in charge of the hospital, told PTI.

"We hope that he will improve in the next few days. We have formed a five-member team," she said.

Meanwhile, the health condition of six others who are also on fast started showing signs of decline, said another junior doctor Debasish Halder, who is present at the protest site in Esplanade area in central Kolkata.

"We have kept all the necessary medical support like an ICU ambulance and others ready here so that we can manage if anyone requires hospitalisation," he said.

Halder said that their fasting would continue until their demands were fully addressed by the state government.

The health condition of the two other junior medics at the North Bengal Medical College and Hospital, who are also on fast unto death, has deteriorated, another health official said.

"We will not withdraw our hunger strike whatever the situation is... and those on fast are unwilling to call it off. Some others are likely to join the fast-unto-death demonstration by today. But I tell you, the state government will be solely responsible for whatever happens to them," Halder said.

Senior doctors concerned about the health condition of the junior medics have appealed to them to withdraw the hunger strike.

"These young doctors are our future. How can the state government be so insensitive? They must act fast before things go out of hand," Dr Hiralal Konar, one of the joint convenors of the Joint Platform of Doctors, West Bengal, told PTI.

The protesting doctors have been demanding justice for the deceased woman medic at the RG Kar Medical College and Hospital and immediate removal of Health Secretary NS Nigam.

Their other demands include the establishment of a centralised referral system for all hospitals and medical colleges in the state, the implementation of a bed vacancy monitoring system, and formation of task forces to ensure essential provisions for CCTV, on-call rooms, and washrooms at their workplaces.

They are also demanding increased police protection in hospitals, recruitment of permanent women police personnel, and swift filling of vacant positions for doctors, nurses, and other healthcare workers.

The junior doctors went on to cease work following the rape-murder of a fellow medic at RG Kar Medical College and Hospital on August 9.

They ended their stir after 42 days on September 21 following assurances from the state government to look into their demands.