Russia is on its way to sharply limiting the adoption of children by people from countries that allow same-sex marriage.

Under a measure that passed its crucial second reading in the lower house of parliament Tuesday, Russia will prohibit adoption by foreign couples whose homeland recognizes their union as marriage, as well as by single people or unmarried couples from those countries.

The lower house voted for the bill unanimously. After a third and final reading that is largely a formality, it must still be passed by the upper house, which is little more than a rubber-stamp body. Then it would go for signing to President Vladimir Putin, who has already expressed support for the ban.

The measure is the latest move by Russia to buck the Western trend toward greater acceptance of homosexuality. The lower house last week overwhelmingly passed a bill that bans giving children so-called homosexual propaganda, which effectively appears to mean any information about gays.

Although Russia lifted the criminalization of homosexuality two decades ago, a widespread hostility toward gays is shared by much of Russia's political and religious elite. Lawmakers have accused gays of decreasing Russia's already low birth rates and said they should be barred from government jobs, undergo forced medical treatment or be exiled.

If it becomes law, the adoption bill would further shrink the possibilities for the estimated 600,000 Russian children who are without parental custody. Last year, Russia banned all adoptions by Americans. That ban came in retaliation for a U.S. law allowing sanctions on Russians deemed to be human rights violators and reflected Russian allegations that U.S. authorities have been negligent and shamefully lenient in investigating and prosecuting abuse and deaths of adopted Russian children.

For Russians, the law allows single people to adopt, but says couples who want to adopt must be married.