MOSCOW: A 14-year-old Russian orphan with a debilitating genetic disease has asked President Vladimir Putin for the right to live with his prospective adoptive family in the United States, news reports said Thursday.

The letter from a boy identified as Maxim in the industrial Ural Mountains city of Chelyabinsk came two weeks after Putin signed into law a bill banning all US adoptions.

The measure was adopted in reprisal for new US legislation that targets alleged Russian rights abusers.

But it also created controversy at home and is expected to see up to 20,000 people come out on the streets of Moscow in protest on Sunday.

Chelyabinsk media said the boy had communicated with the American family for seven years and that his case was already under review when Putin signed the ban into law on December 28.

"I would be very grateful if you come out in favour of children," the website of local Chelyabinsk television quoted Maxim's letter as saying.

The Kremlin's local children's rights representative said the chances of Putin changing his mind at this point seemed remote.

"Maxim has strong relations with his American family and I do not think those bonds should be broken," the Chelyabinsk.ru website quoted envoy Margarita Pavlova as saying.

"It is hard to say how the situation will develop from here. Perhaps they will adopt some amendments to the law," she added in reference to Maxim's chances of leaving Russia.

"But the probability is very low."

Foreign adoptions are a sensitive issue in Russia because the practice of adopting has never truly taken hold among Russians themselves.

The Soviet Union raised all disadvantaged children together in vast collective homes, many of which continue to operate today across the country.

Most foreign adoptions are made by Americans -- nearly 1,000 were recorded last year -- while Russia is the third-most popular country for US nationals seeking to adopt.

Putin's law terminated the processing of nearly 50 cases that had been under review by the Russian courts.