An African regional bloc says South Sudan's government has accepted the deployment of a regional force to the country, almost a month after fighting erupted between opposing army factions.

South Sudan had previously rejected an outside force, but the head of the Intergovernmental Authority on Development said Friday night that the government had accepted a protection force without preconditions.

Mahboub Maalim spoke to reporters after several regional heads of state met on the crisis.

He also said the recently named First Vice President, Taban Deng Gai, has agreed to step down if opposition leader Riek Machar returns to South Sudan's capital, Juba.

Machar, who had been first vice president, fled the capital into hiding shortly after the fighting began last month. His rival, President Salva Kiir, replaced him with Taban.