A U.S. mother who sent her adopted son back to Russia unaccompanied on a plane last April is holding up the boy's re-adoption by refusing to give up her parental rights, children's ombudsman Pavel Astakhov said Tuesday.

Torry Hansen, 33, told a Tennessee court that she only put Artyom Savelyev, now 8, on a plane because "he asked to see his [biological] mother and she let him go," Astakhov wrote on Twitter.

Hansen sent the boy with a note saying he was psychologically unfit and asking that the adoption be cancelled.

But Astakhov called Hansen's court testimony "cynic slyness" that aimed to avoid making child support payments.

Savelyev cannot be re-adopted by another family until Hansen gives up her parental rights.

Astakhov said he would send documents to the Tennessee court to support an attempt by U.S. prosecutors to collect child support payments from Hansen and deprive her of her parental rights. He did not specify how much she is expected to pay.

Savelyev's return angered the Foreign Ministry and prompted calls for a freeze of foreign adoptions until the signing of a bilateral deal with the United States on child adoptions.

Astakhov said last week that other countries will also have to sign similar agreements with Russia in order for their citizens to adopt Russian children, RIA-Novosti reported.

The pact with the United States and one with France will be signed this year, Astakhov said, without elaborating on the time frame.

The Moscow City Court approved 179 of 180 requests by foreign parents to adopt Russian children last year, Astakhov said Tuesday.

U.S. families have adopted more than 14,000 children from Russia over the past five years, including 1,500 in 2009. Another 3,500 Russian children are awaiting adoption by U.S. parents after the adoption process essentially halted in May, according to the Joint Council on International Children’s Services, which represents many U.S. adoption agencies.

About 120,000 Russian children are placed in orphanages every year.