An Afghan teenager and her family have been attacked with acid in northern Afghanistan, after reportedly rejecting a marriage proposal.

The girl, Mumtaz, had been proposed to by a former militia commander. Her parents say the family turned him down and Mumtaz got engaged to someone else.

A group of armed men burst into their home in Kunduz city this week, and attacked the family. The men beat the parents and their three daughters and then sprayed acid on Mumtaz's face before fleeing.

Afghan officials have launched an investigation into the attack and authorities were searching for the assailants.

Human rights activists have expressed concerns about the protection of women as international forces begin withdrawing from the country.

Under Taliban rule in the 1990's women in Afghanistan were not allowed to go to work, get an education or leave the house without being escorted by a man.

Oxfam said in October that a law criminalizing practices such as honor killings and child marriages is only being enforced in 10 out of Afghanistan's 34 provinces.

In the second quarter of 2011 alone, the Afghan Independent Human Rights Commission registered more than 1,000 cases of violence against women.