At 34, Svetlana Bakhmina had it all: the mother of two young boys enjoyed a highflying career as a leading corporate lawyer in Russia’s largest oil company, Yukos.

Five years on, and heavily pregnant with her third child, Bakhmina is now languishing in a remote women’s prison colony after being sentenced to 6½ years on embezzlement charges that most believe were trumped up when Yukos was forced into bankruptcy by the Kremlin. Her case has become the litmus test for pledges made by Dmitry Medvedev, Russia’s new president, to put an end to the country’s “legal nihilism” and reform the justice system.

Bakhmina made a desperate appeal for a presidential pardon 10 days ago, as Medvedev has the power to release convicts on humanitarian grounds. Under Russian law she had to admit she was guilty, even though she has always maintained her innocence. Having served four years of her sentence, Bakhmina, now 39, has twice been denied early release. Some 75,000 people have signed a petition calling for her release before she gives birth in jail. The figure is a record in a country where few believe in their power to influence the government.

Russians have been especially moved by the plight of Bakhmina’s two children, now seven and 11, who do not know their mother is in jail and believe their father when he tells them she is away working. He is allowed to visit her several times a year.

Yelena Bonner, the widow of Andrei Sakharov, the Soviet nuclear physicist who won the Nobel peace prize, has written an open letter asking for Bakhmina’s release.

“Svetlana Bakhmina has already completed the greater part of her term,” said Mikhail Gorbachev, the former Soviet president, who backs the campaign. “She has two little boys, is pregnant and is due to give birth in December. Why hold her behind bars?”

Only two days after she had formally appealed to Medvedev, prison authorities claimed Bakhmina had withdrawn her request. Her lawyers were denied access to her last week after prison guards said she was too sick to talk and had been moved to a hospital.

People familiar with the case suspect Bakhmina was forced to halt the appeal to avoid giving the impression that Medvedev had succumbed to public pressure. In return, she may have been promised an early release.

Bakhmina is widely believed to be a victim of a witch hunt. Until late 2003 she was deputy head of Yukos’s legal department. The oil giant was then owned by Mikhail Khodorkovsky, formerly Russia’s richest man, who fell out with Putin over the businessman’s political ambitions.

Khodorkovsky was jailed for fraud and embezzlement and is serving an eight-year sentence. Several other top Yukos figures are in jail and others, such as Bakhmina’s boss, fled to London. She stayed behind and took over the company’s legal department. Within a week she received her first summons to the prosecutors’ office.

Less than three months later she was arrested and charged with helping to embezzle £150m from a subsidiary company, which has since stated that it is not missing any funds.

She spent two years in a remand prison in Moscow where at one point she shared a cell with 20 other women. For more than a year she had no contact with her children, then aged seven and three, and her eldest child believed she had died.

“Never, not in my wildest dream did I ever imagine I could end up in this situation,” she wrote. “I still can’t understand how these judges could behave the way they did when it’s clear that I’ve very little to do with this whole thing. I wanted to scream to them ‘Why?’ but now I think that God will judge them.”

Following her trial, her living conditions grew worse when she was transferred to a female prison colony 250 miles southeast of Moscow. She lost 18lb in her first two weeks there.

She now shares a barracks with 90 other prisoners. There is no hot water and lavatories are outhouses in the prison yard, where temperatures drop to minus 40C in winter. The prisoners are allowed to wash only once every 10 days. Bakhmina works eight hoursa day as a seamstress and earns £5 a month.

Last March Bakhmina saw her children for the first time in more than three years when she was allowed home for 10 days for good behaviour. That was when she became pregnant. “Being reunited was wonderful of course, but going back to jail after that was terribly hard,” said a close friend.

Her lawyers still hope she will be released before the birth. “Svetlana is a very strong person. She has not been broken. If anything she’s stronger,” said her lawyer.

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