* Unclear exactly how many U.S. adoptions will be cleared
* Russian ban on U.S. adoptions was imposed on Jan. 1
* Law has upset rights campaigners in Russia and ties with US
A number of American couples whose adoptions of Russian children were in the final stages of approval before Moscow imposed a ban breathed a sigh of relief on Tuesday when a court said their adoptions could go ahead.
The precise number that will be allowed is unclear. President Vladimir Putin's spokesman said last month that six adoptions that had been approved by Russian courts would go through, while another 46 that were still under way would not.
Rebecca and Brian Preece from Idaho, who hope to fly home with 4-year-old Gabriel, a boy with Downs Syndrome, said Tuesday's ruling was "the news that our judge has been waiting for".
"Now hopefully, hopefully, hopefully she will issue the decree," Rebecca Preece told Reuters. "This is the most emotionally difficult thing I have had to go through."
The couple have already had to postpone their return flights as their agonising wait for a decree that will allow them to apply for Gabriel's passport, exit visa and adoption certificate has dragged on for 10 days.
Along with dozens of others, their adoption request had been in limbo since President Vladimir Putin signed the ban, which took effect on Jan. 1.
The ban is part of a package of legislation that responds to a U.S. law known as the Magnitsky Act, which excludes Russians from the United States who are suspected of involvement in the death in custody of anti-graft lawyer Sergei Magnitsky in 2009 or of other human rights violations.
Russia's Supreme Court ruled that, in cases where the adoptions had been approved by courts before the new year, the children should be handed over to their adoptive parents, it said on its website.
Russia had about 110,000 orphans living in state institutions in 2011. They are eligible for foreign adoption only after repeated attempts to find them a home in Russia.
Americans have adopted more than 60,000 Russian children since the collapse of the Soviet Union in 1991, according to the U.S. State Department. From 2000 to 2010, the figure was more than 1,000 every year, with a high of nearly 6,000 in 2004.
In approving the ban, Russian lawmakers pointed to abuse by adoptive parents, including the deaths of 19 Russian-born children adopted by Americans in the past decade. They say U.S. courts have been failed to prosecute these abuses properly.
Critics of the measure say it will deprive thousands of children, many of them ill or disabled, of their best hope of escaping Russia's overburdened state institutions.