Tens of thousands of people petitioned President Vladimir Putin Tuesday to release a mother of seven accused of treason for having called the Ukrainian embassy about Russian troop movements.
Svetlana Davydova, who faces between 12 and 20 years in prison, is being held in the high-security Lefortovo jail in Moscow.
She was still breastfeeding her youngest child, a two-and-a-half-month-old girl, when she was arrested last month in the town of Vyazma, west of Moscow.
The case has shocked the country, and led over 50,000 Russians -- including prominent authors, directors and TV celebrities -- to sign an open letter to Putin.
"Mr President, we ask you to be merciful towards a woman and mother of a large family," the letter reads.
"We are hoping that investigation and a possible trial will be as open and just as possible and will be in accordance with the norms of the law."
Among the signatories are Natalya Solzhenitsyna, widow of the Nobel literature prize-winner Alexander Solzhenitsyn, film director Andrei Zvyagintsev and actresses Chulpan Khamatova and Lia Akhedzhakova.
Putin spokesman Dmitry Peskov told AFP Tuesday that the presidency had received the petition and would consider it in due course.
Davydova, 36, who opposes the Ukraine conflict, phoned the Ukrainian embassy last April to allegedly report the military base in Vyazma had emptied, suggesting its soldiers might have been deployed across the border.
She also purportedly informed embassy staff she had overheard a serviceman saying troops of the Russian military intelligence service, the GRU, would be sent on a mission -- presumedly to Ukraine.
Observers call Davydova's case a huge embarrassment for authorities and their virtual blackout of any information regarding Russia's intervention in Ukraine.
Critics also describe Davydova's treatment as reminiscent of excesses by the repressive Soviet regime, and intended to signal the government's willingness to ramp up efforts to squelch dissent.
Akhedzhakova, one of the country's best-loved and most outspoken actresses, said she would do "absolutely everything" to help the woman.
"This is a signal of unthinkable monstrosity, this is 1938," she said on radio, referring to the height of Stalin-era repression.
Authorities had previously said Davydova risked losing custody of her children. But Tuesday, Russia's ombudsman for children's rights said Davydova's husband was taking good care of the children, and that they would remain together as a family.