The UN Security Council on Friday authorized the deployment of a robust force of 4,000 troops to South Sudan after heavy fighting set back efforts to end the country’s devastating war.

The UN Security Council on Friday authorized the deployment of a robust force of 4,000 troops to South Sudan after heavy fighting set back efforts to end the country's devastating war.

The council adopted a US-drafted resolution that also threatened to impose an arms embargo on South Sudan if the government blocks the deployment.

Eleven countries in the 15-member council voted in favor of the resolution. China, Russia, Egypt and Venezuela abstained from the vote.

African leaders called for the regional force to secure Juba and help protect UN bases after a flare-up of violence in the capital that left hundreds dead in early July.

Ethiopia, Kenya and Rwanda are expected to contribute the bulk of the new troops who will be authorized to "use all necessary means, including undertaking robust action where necessary" to fulfill their mandate.

The force will ensure security in Juba and at the airport and "promptly and effectively engage any actor that is credibly found to be preparing attacks or engages in attacks."

That provision could apply to government forces, who stormed a UN base in the northeastern town of Malakal in February, leaving 30 civilians dead.

Under the measure, the council will consider imposing an arms embargo on South Sudan if UN Secretary-General Ban Ki-moon reports that there are "impediments" to the deployment.

Ban will deliver a report to the council in 30 days and a vote on the arms embargo could take place in the following five days if he finds that the government in Juba is uncooperative.

South Sudan's devastating war has raged for two and half years, fueled by growing stockpiles of weapons.

Britain voiced disappointment that the arms embargo was not imposed immediately with Deputy Ambassador Peter Wilson telling the council: "We must and we will return to this issue."