MOSCOW — The upper chamber of Parliament on Wednesday unanimously approved a bill to ban adoptions of Russian children by US citizens, sending the measure to President Vladimir Putin, who has voiced support but not yet said if he will sign it.

Enactment of the adoption ban, which was developed in retaliation for a US law punishing Russians accused of violating human rights, would be the most severe blow yet to relations between Russia and the United States in a year marked by a series of setbacks.