A better cell, a hospital stay or early release -- everything can be bought in Russian jails, as corruption revelations have shown.

Yelena Fedoseyeva, a former inmate at Prison Camp No. 7 near the city of Kaluga, around 180 kilometres (112 miles) southwest of Moscow, recalled how she was asked for a bribe.

"At the end of 2014, Darya Antonova, who was in charge of prisoner education at the No. 7 camp, asked my ex-husband for the equivalent of $2,600 in exchange for my early release," she told AFP.

Six months after he paid the necessary amount -- officially to "buy bedsheets" for prisoners -- Fedoseyeva said she was released.

Wealthier prisoners convicted of financial crimes as Fedoseyeva was -- known as "sweet" inmates in prison slang -- are the main targets of such attempts to extort funds.

In July, the families of inmates at the prison camp where Fedoseyeva served her sentence accused the governor of organising large-scale fraud.

The prison governor allegedly forced families to buy items of equipment for the prison and then got reimbursed by the state, using invoices provided by the families.

"The governor has been removed from her job and is currently under investigation," a spokesman for the regional Investigative committee, which probes serious crimes, told AFP.

"You pay bribes to get a cellphone or medication, to be put in hospital, to get married or have a shower -- everything is for sale in prison," said Inna Bazhibina, an activist for Rus Sidyashchaya, or Russia in Jail, a movement that defends prisoners' rights.

Prices vary according to the prison, said Bazhibina, an accountant who spent two years behind bars on a smuggling charge before being released in 2011.

She recalled that a former businessman complained recently the "monthly rent" for his cell at Medvedkovo penal detention centre in northeast Moscow was excessively high -- around a million rubles (12,000 euros, $13,000), she said.

"Transfer to a better cell at Moscow's penal detention centre Number 1 (known as Matrosskaya Tishina) costs 50,000 rubles," said Yelena Masyuk, a journalist and member of the Kremlin's rights council who visits prisons.

"It costs more at Moscow's Butyrka prison," she added, using the informal name for the city's No. 2 penal detention centre in historic buildings.

"To get hospitalised costs between one and two thousand dollars, depending on the camp and your state of health," said former Soviet dissident and rights activist Valery Borshchev, who also visits prisons to check on their conditions.

"All these reported cases will be checked," the prison service's spokewoman Kristina Belousova told AFP. "The battle against corruption is continuing."

- Rampant violations -

Investigations into corruption in the prison service have uncovered rampant violations involving officials.

In late January, the governor of Prison Camp No. 2 in the city of Kazan in central Russia killed himself after his deputy was arrested and confessed to handing prison management the equivalent of about 600,000 rubles from a prisoner in exchange for early release.

In 2012, the former deputy head of the far eastern Khabarovsk region's prison service committed suicide while facing accusations of corruption. His predecessor had killed himself six months earlier, also while facing fraud charges.

Last year three members of staff and two former employees at Moscow's penal detention centre No. 1 were arrested for allegedly extorting 10 million rubles from prisoners.

Corruption allegations go up to the very highest level: General Alexander Reimer, the head of Russia's prison service until 2012, was arrested in March last year.

He was accused of stealing some three billion rubles from a state contract to buy electronic bracelets and accompanying surveillance systems.