Zimbabwe's Constitutional Court has outlawed child marriage in an effort to end a practice that a rights group says is common in the southern African nation.

The Constitutional Court on Wednesday struck down provisions in the country's marriage laws that allow girls to marry at 16 and boys at the age of 18. Under the new provisions, neither boys nor girls may marry until the age of 18.

The case was brought to the Constitutional Court by two young women who were both forced to marry when they became pregnant as teenagers.

A Human Rights Watch report said a third of Zimbabwean women were married before the age of 18. The groups said girls as young as 12 were married off due to poverty or religious and customary practices.