The UN Assistance Mission in Afghanistan (UNAMA) said the country had far to go in implementing the Law on Elimination of Violence against Women.
The 2009 law made child marriage, forced marriage, forced self-immolation and other violent acts including rape a criminal offence.
"Progress in addressing violence against women will be limited until the law is applied more widely," Georgette Gagnon, director of UNAMA's human rights unit, said.
"So we are calling on the Afghan authorities to take much greater steps to both facilitate reporting of incidents of violence against women and actually open investigations and take on prosecutions."
l Afghan officials are said to be stonewalling US efforts to help regulate the billions of dollars in cash being flown out of Kabul airport every year, US watchdog the Special Inspector General for Afghanistan Reconstruction said in a report published yesterday.