The United States will circulate a UN Security Council draft resolution later this week to create a mechanism to impose sanctions on South Sudan, allowing the world body to target leaders on both sides of the country's nearly yearlong conflict, according to diplomatic sources on the Security Council.

The US delegation told members of its plans during a Tuesday evening session that included a briefing from Ellen Margrethe Løj, head of the UN mission in South Sudan (UNMISS).

Sources close to the negotiations told VICE News that preliminary drafts of the resolution included asset freezes and restrictions on travel, but not an arms embargo — something observers and rights groups have sought for months.

The decision to include an arms embargo alongside sanctions would be a delicate one, given the involvement of Ugandan forces fighting alongside government troops in South Sudan. Uganda is a member of the regional bloc IGAD, which has overseen fruitless peace negotiations. The Security Council and the US government have continued to express support for IGAD, despite its lack of results and conflicting interests.

UK ambassador Mark Lyall Grant tweeted during the Tuesday session that the Security Council was "united behind IGAD's mediation efforts."

In a separate tweet, Grant said he believed an arms embargo should be on the table — a sentiment echoed by Australia, which holds the Security Council presidency during November.

"A number of countries, including ourselves, suggested we have an arms embargo as part of the sanctions package," Australian ambassador Gary Quinlan said after the Security Council adjourned.

The current war in South Sudan began last December, when forces nominally loyal to former vice-president Riek Machar took up arms against the government of President Salva Kiir. The fighting has largely — but not always — split the country along ethnic lines, with Nuer groups supporting Machar and Dinkas backing Kiir.

More than 10,000 people have died in the conflict and 1.9 million have been driven from their homes since December. A lull in fighting brought on by the country's wet season has showed signs of ending as the rains have ceased, with rebels and government forces clashing last week in and around Bentiu, a strategic oil hub.

Quinlan said efforts by IGAD to convene further talks this week with Machar and Kiir have not been successful. "There's a growing sense of frustration among Council members," he told reporters.

The targeted sanctions would come on top of American travel bans and asset freezes imposed by the US on individuals on both side of the conflict in May.

The UN announcement came while South Sudanese president Salva Kiir was on a trip to the Sudanese capital of Khartoum. Sudan has been accused of meddling in the violence in its southern neighbor, which voted for independence in 2011.