By Aaron Maasho
ADDIS ABABA, May 7 (Reuters) - South Sudan's government said on Wednesday it had ordered a one-month suspension of attacks on rebel forces as international pressure mounts for an end to an ethnic conflict that has raised fears of genocide.
South Sudanese Information Minister Michael Makuei Lueth said the government's commitment to honour a "month of tranquillity", proposed on Monday at peace talks in Ethiopia, meant the army could still fight back if attacked.
There was no immediate word from the rebels.
"We have already given our forces an order," Lueth told a news conference in the Ethiopian capital Addis Ababa, where months of peace talks have made little progress.
A ceasefire deal struck in January swiftly fell apart, with each side blaming the other for fighting that has exacerbated deep-rooted tensions between President Salva Kiir's Dinka people and the Nuer tribe of his sacked deputy president, Riek Machar. The conflict has largely followed ethnic faultlines.
Kiir and Machar are due to hold face-to-face talks in Addis Ababa on Friday.
U.S. Secretary of State John Kerry said in Juba last week that Kiir had committed himself to talks on a transitional government, and has threatened Machar with sanctions if he does not meet Kiir.
South Sudanese Foreign Minister Barnaba Marial Benjamin told Reuters on Wednesday that the plan envisaged a "transitional process" that would last until the next election in 2015.
"President Kiir will stay in power until the elections take place," he said.
Machar has called for Kiir to resign, saying he lost the people's trust after fighting broke out in the presidential guard in December and quickly spread across the country, which is about the size of Texas.
Thousands of civilians have been killed, and hundreds of thousands have fled their homes.
In a sign of growing frustration at the failure of South Sudan's leaders to end the bloodshed, the United States on Wednesday imposed sanctions on two commanders on opposing sides of the ethnic violence.
The sanctions were imposed under an executive order that U.S. President Barack Obama signed in April to hold to account those responsible for the unrest in South Sudan - whose secession from Sudan in 2011 was seen as a major U.S. policy success.
Norway, another of South Sudan's main Western sponsors and donors, also made clear that its patience was running out.
"We made it clear that the international community will react even firmer in the coming months if they don't take responsibility in ending the fighting and find a solution for an inclusive government for the future," Norwegian Foreign Minister Borge Bende told Reuters in Addis Ababa.
Benjamin said in Juba that he had understood from Kerry that the regional African group IGAD, which is sponsoring the peace talks, would take the lead on any foreign sanctions.
"We were surprised that the United States pre-empted what they had agreed upon," he said, although he added that he doubted relations with Washington would be damaged.
The sanctions targeted Peter Gadet, an army commander loyal to Machar, and Major-General Marial Chanuong, head of Kiir's presidential guard. One U.S. official said both men had "blood on their hands". (Writing by Richard Lough; Additional reporting by Andrew Green in Juba; Editing by Edmund Blair and Kevin Liffey)