The U.N. approved the deployment in August after days of heavy fighting in Juba between troops loyal to President Salva Kiir and those backing former Vice President Riek Machar. There are already 13,000 U.N. peacekeepers in South Sudan.

South Sudan four-year civil war triggered by Kiir's sacking of Machar as his deputy. The men come from rival ethnic groups and the fighting, which has uprooted a quarter of the country's 12 million people, has been largely along tribal lines.

The U.N. Secretary General's special representative in South Sudan, David Shearer, told a news conference that the recruits, who arrived this weekend, would join a battalion from Nepal and Bangladesh attached to the regional protection force (RPF).

“The arrival of this contingent ... marks the beginning of the phased deployment of the RPF," Shearer said. More troops were also expected to be deployed from Ethiopia, he said.

The RPF is mandated to enforce peace in Juba and protect the capital's sole international airport and other important facilities as well as stopping anyone "preparing attacks, or engages in attacks" against U.N. sites, aid workers or civilians and would confront South Sudanese government troops if needed.

"Having additional troops means we can carry out more tasks related to our mandate to protecting civilian and build a durable peace," Shearer said.