The return of the child provoked outrage in Russia
Russia says it has halted adoptions of Russian children by US citizens, after a boy of seven was sent back to Moscow alone by his adoptive American mother.
The Russian foreign ministry said the freeze would apply until a bilateral adoption agreement could be signed.
However the US state department said its Russian embassy had been told there was no such suspension and was seeking clarification from Moscow.
It will send a delegation to Moscow next week to discuss the incident.
There was an international outcry last week when the adoptive mother, a nurse, sent the Russian boy on a one-way flight to Moscow on his own.
She sent a note with him saying the boy had psychological issues.
"To Whom It May Concern," the letter read. "This child is mentally unstable. He is violent and has severe psychopathic issues. I was lied to and misled by the Russian orphanage workers and director regarding his mental stability and other issues."
Torry Hansen, 33, reportedly adopted the boy from Russia's Far Eastern town of Partizansk last September.
The US state department is arranging for a high-level delegation to visit Moscow next week to discuss the possibility of a bilateral adoption agreement.
Russian foreign ministry spokesman Andrei Nesterenko told a TV briefing: "Russia believes only such an agreement
will ensure that recent tragedies in the United States will not be repeated."
Russian Foreign Minister Sergei Lavrov said the incident was "the last straw"
Russians are furious that no charges have been brought; US authorities have been investigating allegations of abuse and child abandonment.
A Tennessee sheriff told a news conference earlier this week that Ms Hansen's lawyer had said she would not talk to the authorities unless charged.
The adoptive family hired a driver in Moscow to deliver the boy from the airport to the Russian ministry of education on Thursday of last week.
The driver, Artur Lukyanov, has told AP news agency that on the way into town the boy had played with toys and told him in English how big the lorries were in America.
A US adoption agency assigned to check on the family, Adoption Assistance, said earlier this week that its officials had not been able to contact Ms Hansen since March.
The agency said in a statement that the child had appeared to be adjusting well during a visit by a social worker in January to the family home in Shelbyville, a town about 80km (50 miles) south of Nashville.
Ms Hansen's mother, Nancy Hansen, has been quoted as saying that the child had threatened to burn the family's home to the ground.
Thousands of American would-be adoptive parents have been petitioning leaders of the Russian and US presidents to prevent the threatened adoption freeze by Moscow.
Russian lawmakers have previously urged the suspension of American adoptions after other alleged cases of Russian children being mistreated.
Russian Foreign Minister Sergei Lavrov has called the most recent incident "the last straw".
More than 1,800 Russian children were adopted in the US last year, according to Russia's health and education ministry.