Students from Russia sitting in a classroom as part of the FLEX program.

Defending Moscow's abolition of the FLEX program, Russia's child rights ombudsman said Thursday that not just one but more than a dozen Russian teenagers who have traveled to the U.S. under various education exchange programs have stayed on in the country permanently.

Russia on Tuesday pulled out of FLEX, saying the U.S. had violated the terms of the exchange by allowing one of its participants to stay in the country after the program ended, later adding the student had been taken in by a homosexual couple — thereby breaking a Russian ban on U.S. adoptions.

Asked by official government daily Rossiiskaya Gazeta whether Russia pulled out of FLEX over that isolated case, children's rights ombudsman Pavel Astakhov said there had been many more irregularities in exchange programs over the years.

"For a number of years already we've been locating our children who traveled to the U.S. as part of cultural, [medical] rehabilitation or tourist programs, and who were kept on in American families," Astakhov said in the interview published on Thursday.

"Today we have at the very least 15 such kids, and we are still working on these cases," he said.

About 8,000 students from Russia have visited the U.S. under the FLEX program during the two decades it has been in place, many of whom are well known figures — such as Margarita Simonyan, the current editor-in-chief of pro-Kremlin international broadcaster RT.

FLEX students are required to return to their home country for at least two years after completing the program and are not allowed to apply for a U.S. immigration visa during that period.

Astakhov: At Least 15 Russian Children Flouted U.S. Exchange Rules