A Christian human rights group says it has bought the freedom of nearly 450 slaves in southern Sudan.

The slaves, who are Dinka tribespeople have been captured during raids by government-sponsored militia in the Bahr el Gazal region.

The area is on the front line in the long-running war between the muslim-dominated government of the north and the rebel south which is mainly Christian.

Martin Dawes watched as money was paid to Arab traders

There were hardly any men captured. Typically it is the women and children who are taken by horsemen from the Arabised neighbouring tribes.

Any men found during these brutal raids are usually killed. Tales of sexual abuse and genital mutilation are common.

Many of the women were pregnant and some had babies. Two mothers told me how they had been raped.

One was assaulted by the son of the man she called master. Another, who was taken as a child seven years ago, said she had become a concubine.

Mnay of the salves have horrific stories to tell

The children are used to look after the animals. They say they were beaten regularly. Two brothers and an older sister sat quietly, apparently with no-one to look after them. The girl said they had not seen their mother for three years.

Two Arab traders brought 449 people to an agreed rendezvous in a rebel-held area.

Even then the women and children are not free - the traders have to be paid.

The two men said they were acting out of principle and that they would be killed if it was known that they were helping slaves return home.

John Eibner, of the Swiss-based Christian Solidarity International, pays the equivalent of $50 per person, mainly in bundles of the Sudanese currency.

He says the price has not risen since they started the scheme in 1995.