“The children who have been chosen by foreign American parents — we know of 46 children who were seen, whose paperwork was processed, who came in the sights of American agencies,” Mr. Astakhov said in his statement. “They will not be able to go to America, to those who wanted to see them as their adopted children. There is no need to go out and make a tragedy out of it.”

Mr. Astakhov, who is a longtime advocate of restricting international adoptions, said he would seek to extend the ban to all countries. “I think any foreign adoption is bad for the country,” he said.

That remark prompted Sergei Parkhomenko, a well-known journalist and commenter, to reply tartly, “Adoption when needed is for the good of the child, not the good of the country.” And he accused Mr. Astakhov of neglecting his duty to serve children in favor of serving Mr. Putin, who appointed him.

Some Russian lawmakers said they believed that the bilateral agreement on adoptions with the United States would be void as of Tuesday, even though Mr. Putin, at his annual news conference last week, said changes to the agreement required one year’s notice by either side.

The proposed ban has opened a rare split at the highest levels of the Russian government, with several senior officials speaking out against it. And it has provoked a huge public outcry and debate, with critics of the ban saying it would most hurt Russian orphans, many of whom are already suffering in the country’s deeply troubled child welfare system.

In their debate on Wednesday, lawmakers said they felt compelled to retaliate for a law signed by President Obama this month that will punish Russian citizens accused of violating human rights, by prohibiting them from traveling to the United States and from owning real estate or other assets there.

Lawmakers also said that Russia, which has more than 650,000 children living without parental supervision, should take care of them on its own. At the same time, the lawmakers acknowledged the flaws in the system and on Wednesday adopted a resolution calling for measures to make adoption by Russian citizens easier.