As South Sudan rebels battled government troops for control of the flashpoint town of Bor, the AU says it will impose sanctions over violence.
The African Union said it will impose "targeted sanctions" over violence in war-torn South Sudan, where two weeks of fighting is feared to have left thousands dead.
The pan-Africa bloc's Peace and Security Council said in a statement it would "take appropriate measures, including targeted sanctions, against all those who incite people to violence, including along ethnic lines".
Meanwhile, South Sudan rebels battled government troops on Tuesday for control of the flashpoint town of Bor, the army said, dashing hopes a looming ceasefire deadline in the war-torn nation would be heeded.
"There is fighting this morning [Tuesday] in Bor town ... we are awaiting more details," army spokesperson Philip Aguer said. The army celebrated last week the recapture of Bor from the rebel forces, who have been fighting government troops for over two weeks.
Offer of a cease-fire
Late on Monday, Uganda's president warned South Sudan's rebel leader against rejecting the government's offer of a cease-fire, saying regional leaders would unite to "defeat" the former vice-president who is accused of mounting a failed coup in the world's newest country.
Ugandan President Yoweri Museveni told reporters in Juba, the South Sudan capital, that a regional bloc known as IGAD had given Riek Machar "four days to respond" to the cease-fire offer.
"If he doesn't we shall have to go for him, all of us," he said, referring to IGAD.
A meeting of East African leaders last week said it "welcomed the commitment" by South Sudan's government to cease hostilities against rebels and urged both sides to start peace talks by Tuesday. Machar instead called for a negotiated cease-fire that includes a way to monitor compliance.
Violence since mid-December in South Sudan has displaced up to 180 000 people, the United Nations said on Monday.
Uganda's influence is strong in South Sudan, where special forces from the neighbouring country have been deployed at the request of South Sudan's President Salva Kiir, raising questions about the impartiality of Uganda as a possible mediator in a conflict that many fear could lead to civil war in the world's newest country.
But France's ambassador to the United Nations said South Sudan's government has the right under international law to seek help from neighbouring countries to defend itself.
"There is a government in South Sudan, which has the right to ask for another country to support its military efforts," said Gerard Araud, who is the UN Security Council president. He added that the Security Council "does not have a say" in whether South Sudan seeks such help. – AFP, Sapa-AP