Russia barred U.S. families from adopting Russian children effective Jan. 1, but at the time, hundreds of families were already in the process.
"The issue is closed because there is no process," Kremlin children's rights ombudsman Pavel Astakhov said.
About half of the children that were going to be adopted by U.S. parents have already been adopted by families in Russia, placed in foster homes or returned to their biological families, Astakhov said Wednesday.
"We have reiterated our deep disappointment with the Russian government's decision to ban the adoption of Russian children by U.S. citizens," a U.S. State Department official said.
The United States continues "to encourage the resolution of all adoptions that were in process prior to Jan. 1 in the spirit of our bilateral agreement and based on humanitarian grounds," the official said.