South Sudan became independent in July after a 2005 peace deal with Khartoum that ended decades of civil war but the oil-producing nation has been struggling to end tribal and rebel violence that has killed around 3,000 people this year.
The violence threatens to turn the new nation into a failed state and could upset the stability of its east African neighbors.
In the latest incident, youths from Warrap state attacked villages in neighboring Unity state last weekend, officials said on Thursday.
“It’s a disastrous issue. A group with fire-arms came to villages in Mayendit. They came to raid cattle but also killed women and children,” Unity state minister of information Gideon Gatpan said, adding that another 40 people were still missing.
Analysts say cattle theft is on the rise, driven by inflation of bride prices, which are traditionally paid in cows.
At least seven rebel militias are fighting the new government’s forces in remote parts of South Sudan, a country roughly the size of France.
South Sudan has accused Khartoum of supporting militias but the north denies this, and many rebels say they are fighting against what they see as corruption and ethnic discrimination in the south’s government, charges it denies.
