A controversial law banning Americans from adopting Russian children has come into force days after it was signed by president Vladimir Putin.

The law is seen as a retaliatory move against the US, after it passed a bill sanctioning Russian officials accused of human rights abuses.

The US State Department has expressed its regret over Russia's decision to pass the law.

Officials say they hope orphans who have already met and bonded with their American adoptive parents will be allowed to join their new families.