* Conflict continues despite past ceasefire deals
* West and regional states grow more frustrated
* Fighting is leading nation towards famine
By Aaron Maasho
ADDIS ABABA, Aug 25 (Reuters) - East African leaders on Monday gave South Sudan's warring sides six weeks to agree on a transitional government after a deadline earlier this month was missed and fighting rumbled on instead.
Meeting in Addis Ababa, heads of state from the regional African grouping IGAD said the two sides should agree to a plan for setting up a transitional government that would include a new post of prime minister.
President Salva Kiir would keep his post, while rebels loyal to his former deputy Riek Machar would nominate the prime minister, whose powers would be defined in peace talks.
At least 10,000 people have been killed since the conflict between supporters of the two men erupted in December.
Western powers who backed South Sudan's independence from Sudan in 2011 and regional nations leading the peace talks in Ethiopia have voiced growing frustration at the two leaders for a conflict that is leading the nation towards famine.
IGAD said it would "take action against those who obstruct the attainment of peace in South Sudan". It has previously warned both sides of sanctions if they did not stop fighting.
Anyone viewed as impeding peace talks would also be blocked from any future governance arrangements, the group added.
Both factions signed a new document outlining their commitment to a ceasefire on Monday, although two previous peace deals have swiftly been broken with each side accusing the other of violations.
The United States and Europe have already imposed sanctions on commanders from both sides, but diplomats say real pressure for a deal needs to come from neighbouring states.
Under the plan backed by IGAD, the transitional government would run the country for 30 months, with elections held 60 days before that period ends. Kiir's camp has already said it supports that plan but the rebels have so far shunned it.
In the statement released after Monday's meeting, IGAD urged the rebels to endorse the deal. But there was no immediate comment from rebel officials.
IGAD also condemned the detention of a group of ceasefire monitors last week in oil-producing Unity State, in the north of the country. One member of the group died of a heart attack.
Months of peace talks have made little significant progress, with diplomats complaining that both sides have spent more time arguing about procedure than issues of substance.
In the latest dispute, the government boycotted negotiations for more than a week because of a disagreement about who can participate and take decisions at the talks.
The United States has warned both sides of possible sanctions on those impeding the peace talks. (Reporting by Aaron Maasho; Editing by Tom Heneghan)
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