Nadezhda Tolokonnikova was jailed for two years in August 2012, alongside fellow band member Maria Alyokhina, on "hooliganism motivated by religious hatred" charges stemming from a protest they held against President Vladimir Putin in Moscow's main cathedral.
Their punishment drew international condemnation and turned the pair into a symbol of political repression under Putin -- a former KGB spy who has tolerated little dissent during his 13 years in power.
Tolokonnikova was moved to a local hospital on Sunday and put on a drip the following day due to general weakness associated with her strike.
The prison service said Tolokonnikova's health was now "stable".
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Russian human rights activist and leftist parliament member Ilya Ponomaryov confirmed the information after paying a brief visit to her hospital today.
She "stopped her hunger strike for medical reasons," Ponomaryov tweeted.
Tolokonnikova announced her hunger strike after releasing an open letter in which she described harrowing conditions at her prison and claimed that she had received death threats for complaining.