Russian president Vladimir Putin signed into law a controversial new bill reducing punishment for domestic abuse, state news agency TASS reported.

Dubbed the "slapping law", the bill decriminalises first domestic violence offences within families that do not cause serious injury to the victim.

According to the criteria laid down by the Russian Health Ministry "small abrasions, bruises, superficial wounds, and soft-tissue damage" are classified as "minor harm," though repeat offences can result on criminal prosecution.

More than 85% of lawmakers in the Russian state Duma approved the bill in a vote in January – which is seen as part of Putin's agenda to promote conservative values.

Defenders of the bill claim it will help parents who strictly discipline their children avoid prosecution, rather than allowing strangers who attack children to evade punishment.

The bill's sponsors include conservative senator Yelena Mizulina, who was also the author of Russia's controversial "anti-gay propaganda" bill, which criminalises providing children with information about homosexuality.

Mizulina argued the domestic violence bill brings family law into line with reforms passed last summer loosening punishment for other minor assaults, though critics claim it will allow those guitly of domestic abuse to evade punishment.