(CNN) Attackers raped, beat and robbed more than 100 women and girls in northern South Sudan over a 10-day period in November, aid agency Doctors Without Borders (MSF) said.

South Sudan, the world's youngest country , has been embroiled in civil conflict since 2013, with its civilian population paying a heavy price. South Sudan's president, Salva Kiir, signed a peace agreement with rebel leaders in September but it is not yet clear if the agreement will hold.

The unrest has driven nearly 4 million people from their homes , according to UN figures, with hunger and violence widespread.

"Women and young girls have been coming to the MSF clinic in Bentiu en masse over the past week after surviving horrific episodes of sexual violence," Ruth Okello, an MSF midwife in South Sudan, was quoted as saying in an MSF statement Friday.

"Some are girls under 10 years old and others are women older than 65. Even pregnant women have not been spared from these brutal attacks."

Read More