MOSCOW – The 15-year-old twins sleep among trash and dirt in a nook under a railway platform and spend their days at a Salvation Army shelter in a grim Moscow neighborhood.

But Denis and his sister Olesya prefer being homeless to living with their parents in Elektrostal, 36 miles east of the capital. They say their mother abused them physically and verbally, then kicked them out in July, telling them to find jobs.

“It was hard at home, not cozy,” said Denis, who spoke on condition his last name not be used.

The twins are among a growing number of Russia children who face abuse and neglect despite an economic boom that has brought unprecedented wealth.

A report by Russia’s human rights ombudsman says children’s rights violations remain “systematic” and more parents are victimizing their children.

While oil wealth has enriched a minority of Russians, the poverty, social decay and endemic alcoholism that are at the root of the child abuse have deepened since the 1991 Soviet collapse.

Public sensitivity to child welfare is growing, however, as Russians face up to the fact that the population has shrunk by about 4 percent a year since 1993, to 142.7 million. President Putin sounded the alarm in 2006, saying in his annual state of the nation address that the country was on the verge of a demographic crisis and that Russia’s children needed special care.

Official statistics show the number of children has fallen from 36 million to 29 million over the past eight years, part of an overall fall resulting from low birth rates, an antiquated public health care system, poverty, alcoholism and rampant crime.

Child’s Right, a Moscow-based advocacy group, says that every year about 2,000 of Russia’s 29 million children aged up to 17 are killed by their parents or other relatives – which translates into a rate of about 6.9 per 100,000.

By rough comparison, the American Bureau of Justice Statistics reports that in 2005, the overall homicide rate for children 13 and under – regardless of the perpetrator – was 1.4 per 100,000. The overall American rate for children aged 14 to 17 was 4.8 per 100,000.

According to a UNICEF report, the suicide rate for Russian youths aged 15 to 19 was 20.2 per 100,000 in 2004. That’s more than double the rate of 8.2 per 100,000 for the same age group in America in 2004, as reported by the Centers for Disease Control and Prevention.

Child’s Right, citing state statistics, says about 50,000 Russian children – one out of every 580 – run away from home each year. Another 20,000 flee from state-run orphanages and other institutions.

Boris Altshuler, head of Child’s Right, tells the story of 11-year-old Vlad Yakovlev from the Siberian city of Kurgan. According to police, Vlad’s alcoholic mother starved her son, and taunted and beat him. He hanged himself with the belt of a dressing gown one evening in November 2005. This year, Vlad’s mother was sentenced to 2½ years in prison for driving her son to suicide.

“Many people see children as their property. There is no concept that they bear some social responsibility for their children,” said Mr. Altshuler, a 67-year-old physicist who became a human rights activist in the 1970s alongside prominent dissident Andrei Sakharov.

Authorities can either do nothing or take the child away from parents and place him in an orphanage, Mr. Altshuler said, but there is no middle ground such as family counseling or monitoring by social workers, and no law that obliges the state to act.

“The whole country is one orphan-making factory,” he said in an interview.

He said Mr. Putin appears to be trying to reduce the number of children in institutions. But he predicted the bureaucrats who control the $1.5 billion Russia spends each year on orphanages and children’s homes will try to derail the effort.

“They need children like firewood to keep this system going,” Mr. Altshuler said.

According to the human rights ombudsman, the number of orphans or children whose parents were stripped of their custody rights has risen by almost 20 percent over the past eight years, to more than 730,000.

UNICEF data says 1,384 Russian children out of every 100,000 lived in an institution in 2005, compared with 709 per 100,000 in Poland and 590 out of 100,000 in the former Soviet state of Estonia.

In recent years, the Russian government has established a foster home program and created hot lines for child victims. Charities and nongovernment groups have opened shelters and UNICEF is working to create a national network of children’s rights watchdogs.

With the Kremlin raising awareness, the Russian media in recent months has paid more attention to cases such as that of a 7-year-old boy in the mining town of Guryevsk, in southwestern Siberia, who was hospitalized with cirrhosis of the liver; he had been driven to alcohol abuse by his father who wanted a drinking buddy.

This year, prosecutors investigated medical workers at a hospital in the town of Orekhovo-Zuyevo, east of Moscow, who allegedly tied a 1½-year-old girl and a 2-year-old boy to their beds with sheets so they could be left unsupervised. The toddlers had been abandoned by their parents.

Workers at a hospital in Yekaterinburg, in the Ural mountains, were accused of taping infants’ mouths shut to keep them from crying. And on the Pacific island of Sakhalin, authorities said a kindergarten employee gave unauthorized injections to children to calm them or to help them sleep.

“It’s a bit shocking when you see such strong violations of children’s rights going on in a country that has accumulated such huge wealth,” said Carel de Rooy, UNICEF representative in Russia.

Their health is becoming a higher priority, he added. But the change is probably driven more by demographic concerns than greater awareness of children’s rights, Ms. de Rooy said.

At Moscow’s Salvation Army shelter, a spacious room in a gated building, Denis, Olesya, and a dozen other homeless children wash their clothes, play pingpong and watch a video.

The twins still have a hard time talking about their experiences at home.

Did your mother beat you? a visitor asked. Denis looked down and nodded. Were there fights at home? Another nod.

Olesya said she liked her new “freedom,” which means begging for money at railway stations, using drugs and “dating young men.”

She said she’ll think about the future one day.

When? “When I grow up.”