Machar also ruled out an immediate ceasefire, saying this “needed to be negotiated” and that in the meantime the rebels would continue to fight.
“Our forces are still marching on Juba, there is no cessation of hostilities yet,” Machar said, speaking by satellite telephone from an undisclosed location inside South Sudan.
“That is what the delegation is going to Addis Ababa to discuss and to negotiate.”
He said troops loyal to him had recaptured the town of Bor on Tuesday, some 200 kilometres (125 miles) north of the capital Juba.
Machar said he was not yet ready for face-to-face talks with Juba’s leadership.
“It depends on how the negotiations go,” he said.
“I will follow later, once the negotiations have resulted in a cessation of hostilities. It depends on if and when that is achieved,” he added.
“We did not ask for this battle, it was forced upon us,” Machar said, again dismissing Kiir’s allegations that he started the fighting by attempting a coup.
Machar is sending a three person team of senior leaders, including Rebecca Garang, a powerful politician, respected Dinka leader and widow of former South Sudan’s founding father John Garang.
The other two in the delegation are Taban Deng Gai, a former governor of oil-rich Unity state, large parts of which are under rebel control, and Hussein Mar, former deputy governor of Jonglei.
But he also demanded Juba release several key leaders arrested following the outbreak of fighting on December 15, especially Pagan Amum, the former secretary-general of the ruling party.
“They must release the prisoners,” Machar said, adding that Amum was needed to head the rebel delegation at any peace talks.