Government agencies, international bodies and domestic charities give wildly differing estimates of how many children are housed in state institutions, and there are no reliable, up-to-date figures.

About 371,700 children were in Russian institutions in 2009, according to the latest official government data, which were filed with the United Nations last year.

That number is down from 477,400 in 2003 and includes orphans in houses for babies, orphanages and institutions for children with mental and physical disabilities.

The latest numbers from the State Statistics Service put the number of children being raised in state institutions in 2009 at 127,394, down from a post-Soviet high of 186,087 in 2002, according to information on its website.

In 2010, about 260,000 children, or one out of every 100 in the country, were living in 5,186 institutions, said a 113-page report titled "Orphanhood in Russia," published on Philanthropy.ru on March 11 and sponsored by currency brokerage ForexClub.

The actual number of children stuck in institutions could be even higher, said Jo Rogers, project director at Russian charity EveryChild and consultant for the United Nations Children's Fund, or UNICEF.

Rogers has interviewed dozens of child welfare officials in Russian regions. She said that including children in temporary care, where stays can last anywhere from three months to a year, 558,000 children were in institutions in 2008.

In a February survey, UNICEF officially put the number of children in Russian institutions at "more than 140,000," a figure that has not changed substantively since 2000.

Most statistics suggest that the number of children in institutions is decreasing.

"The formal indicators of orphan numbers have objectively fallen," President Dmitry Medvedev said last year.

But the countries of the former Soviet Union and the Warsaw Pact continue to have the highest rates of institutionalization in the world, according to UNICEF.

To achieve reductions, Russian social services need to offer better support for families in very difficult situations so they can continue to bring up their children, said Bertrand Bainvel, the head of UNICEF's office in the Russian Federation.

"On the federal level, there is a need for a systematic approach and a strategic plan, as well as systemic monitoring to assess progress," Bainvel said.

"When there is a systematic plan, there are results … for example, the republic of Karelia, for example the Kostroma region. This is not experience from Mars. It is experience that exists in the Russian Federation."

The trend may be distorted by declines in the total number of children in Russia that dipped below 30 million for the first time in 2007.

UNICEF estimates that there are about 26 million children in Russia today, 7.5 million fewer than in 2000.

And though the number of orphans was lower in 2010 than at any time since 1993, the Philanthropy.ru report raised worrying questions about trends over the past two years, for which no official data are available.

Instances of adoption and foster parenthood have become less frequent, falling by more than a third from 2007 to 2010, authors Lidia Tikhonovich and Andrei Suchilin said.

And the quantity of children being returned to institutions from foster and adoptive families is increasing, from about 18,000 in 2008 and 2009 to about 30,000 in 2010 and 2011.

"Since 2008, a new wave of problems has begun in the battle with orphanhood," the report states.