
The former rebels crossed the border from Sudan to the north in about 100 trucks. Sudan has repeatedly denied accusations that it backs rebel groups in the South.
The South Sudanese information minister told the BBC that the rebels had been pardoned by President Salva Kiir, and would now be integrated into South Sudan's army.
South Sudan seceded from Sudan in 2011, and took most of the country’s oil, although all its pipelines run north into Sudan.