MOSCOW (AFP) - Jailed Pussy Riot punk band member Nadezhda Tolokonnikova has been put on an IV drip in hospital on the eighth day of her hunger strike, a prison doctor said Monday.

Tolokonnikova went on hunger strike on Sept 23, releasing an open letter in which she described harrowing conditions at her prison and claimed that she had received death threats over her complaints.

"She agreed for medicine to be given to her intravenously," Alexander Pozdnyakov, chief doctor at a prison hospital in Russia's central Mordovia region, told AFP by phone.

On a live talk show on state television on Monday evening, the head of her penal colony, Mr Alexander Kulagin, said that she would be force-fed with glucose via her drip if her health worsened.

"So far this is not being used but if necessary, if her state of health gets worse, then on the recommendation of a doctor, on the insistence of doctors, it will be used," he said.

"We are primarily humane people and therefore we will use (this) if her state of health gets worse." The prison administration has taken extraordinary steps to deny Tolokonnikova's accusations, which have caused a wave of public debate.

The deputy head of the colony, Yury Kupriyanov also appeared on Rossiya 1 television to deny Tolokonnikova's claim that he had hinted she could be killed by her fellow prisoners.

"There is no pressure, no one is threatening her," Mr Kupriyanov said.

The regional prison service said Monday evening that due to her refusal of food, she was being given "all necessary qualified medical aid." It said she could only be visited by medical staff on doctors' orders.

Tolokonnikova's husband Pyotr Verzilov said Monday the 23-year-old had been held incommunicado for 90 hours.

The activist, who stopped eating to protest what she described as "slave labour conditions" and death threats, was transferred on Sunday to hospital from her Mordovia prison colony, where she was moved last week to an isolation cell.

Tolokonnikova has said she will refuse food until she is transferred to another jail.

She is serving a two-year sentence for performing a protest song against President Vladimir Putin in Moscow's main cathedral last year.

Verzilov said authorities at the prison hospital had denied his request to see his wife, and had also refused to allow the couple to speak by phone.

"They explained it by the fact that her state of health is so bad that she cannot speak with her defence," he said.

On Sunday, Verzilov issued an open letter addressed to the head of the Federal Service for the Execution of Punishment, which oversees prisons, protesting that Tolokonnikova was being held incommunicado.

On Monday, one of her lawyers filed a complaint about the conditions at her prison to the Office of the UN High Commissioner for Human Rights.

"The situation in which Ms Tolokonnikova finds herself in the correctional colony no. 14 in Mordovia, Russia constitutes one of the abhorrent contemporary 'slave-like' practices," lawyer Sergei Golubok wrote in English.

Tolokonnikova's open letter ignited a fresh debate about filthy jail conditions and prisoner abuse.

Rights activists have for years sounded the alarm over prison conditions in modern Russia, but few complaints from female jails have previously been made public due to what activists describe as a culture of violence and intimidation.

"Tolokonnikova has done more to attract attention to the problem of prisoners' rights than heaps of rights activists in recent years," opposition politician Alexei Navalny wrote on Twitter.

Several prominent figures called on the young mother to stop her protest.

"Unfortunately, our society only reacts to extreme situations," veteran rights activist Lyudmila Alexeyeva said on Moscow Echo radio.