South Sudan's rebel leader dashed hopes of a ceasefire yesterday, complicating a frantic diplomatic effort to halt the country's civil war.
But Riek Machar, whose insurgents now control the biggest oilfields in the world's newest nation, did not attend the meeting and made clear that his forces would not comply.
"I have got involved many times in negotiating ceasefires," said Mr Machar.
"My knowledge of it is that ceasefires are negotiated by two delegations and then mechanisms for monitoring the ceasefires are put in place, so that a ceasefire becomes a credible ceasefire."
Mr Machar said that he was not bound by the conclusion of a meeting he did not join.
Thousands are believed to have died in two weeks of fighting between Mr Machar's rebels and government forces. About 120,000 people have been driven from their homes, with more than 60,000 sheltering in UN compounds across the country.
Mr Machar said his forces had captured all of Unity state and "three quarters" of Upper Nile state, which together produce South Sudan's daily oil output of 245,000 barrels. In addition, he claimed to hold all of Jonglei state, apart from its capital, Bor. Mr Kiir controls the national capital, Juba, and the other seven states.
By seizing the oilfields, Mr Machar is trying to maximise his bargaining power in any future negotiations. His feud with Mr Kiir is primarily a struggle for power: Mr Machar was sacked as vice-president in July and accuses the president of plotting to become a dictator. But the conflict also reflects a widening tribal fissure between Mr Machar's Nuer people and the president's Dinka ethnic group.
So far, there have been no direct talks between the two rivals, or their representatives. Mr Machar said he was willing to negotiate, but he first demanded the release of 11 allies, who were jailed and accused of mounting a coup when the fighting started in Juba on December 15.
Mr Kiir has freed two of these detainees -- and mediators say that "most" are expected to be let out. But he insisted that all must be released before any talks can begin.
Britain, America and Norway serve as guarantors of the peace agreement that allowed South Sudan to secede from its neighbour and achieve independence in 2011. William Hague, Britain's foreign secretary, pledged that all three countries would work "in lockstep" to restore peace.
Mr Machar has not disclosed his own location, saying only that he is "in the bush" in South Sudan. His allies are either in prison in Juba, or directing military operations.
However, Mr Machar disclosed that he spoke by satellite telephone to John Kerry, the US secretary of state, twice last Thursday. America gave vital support to South Sudan during the last decade of its struggle for independence against rule by Khartoum.
Mr Machar, who graduated in mechanical engineering from Bradford Polytechnic in 1984, accused Mr Kiir of "plunging" South Sudan into an "unnecessary conflict". He added: "We want South Sudan to be a democratic nation with free people, elections which are free and fair, multi-partyism where power transfers through the ballot box."
Mr Kiir stands accused of leading an autocratic and militarised government which has failed to create a viable state. Instead, corruption has undermined South Sudan's young institutions from the moment of their birth.
Fierce fighting continues, with the latest clashes taking place in Malakal, the capital of Upper Nile State.
Yesterday there were reports that 25,000 young men who make up a tribal militia known as the 'White Army' are marching towards a contested state capital in South Sudan. The youths from the Lou Nuer sub-clan -- the same tribe Mr Machar is from -- are marching on Bor, said information minister Michael Makuei Lueth. The "White Army" gets its name in part from the white ash fighters put on their skin to protect them from insects.
"He has decided to mobilise the youth in the name of his tribe," Mr Lueth said.
The White Army has threatened the central government in the recent past.
James Koang Chuol, a rebel commander, denied that the insurgents were seeking to dominate the oilfields and form a state within a state.
"The unity of South Sudan is very important. We have to contain this incident and find a solution," he said.
Both sides also deny that the war is becoming a tribal conflict between Nuers and Dinkas. In Juba, however, about 10,000 Nuers have sought sanctuary in a UN compound next to the airport. They say they were targeted for attack by Dinka soldiers.
"When the fighting was happening, we didn't know that it was going to be an issue with civilians," said one man. "But soldiers, who are Dinka, came and carried out a house to house search, asking 'are you a Dinka, or a Nuer?' If you are a Nuer, you are shot. My two cousins were killed."
Duncan Woodside in Nairobi