Forty-eight hours after the latest ceasefire deal in South Sudan, a battle broke out on Monday between government troops and rebel fighters in which 29 combattants died, said a military spokesman.

South Sudan military spokesman Col. Philip Aguer said the fighting killed 24 rebels and five government soldiers. There was no way to independently verify Aguer's casualty toll.

Aguer blamed the battle on rebels, saying they launched an attack on government positions in the northern part of Upper Nile state. A rebel spokesman said that government forces launched the first attack.

"The government is entirely responsible for these unnecessary attacks motivated by its desires and attempts to recapture oil fields under our control before a permanent cessation agreement could be signed," said rebel spokesman Brig. Gen. Lul Ruai Koang.

Political leaders in Ethiopia early on Saturday agreed to the third cease-fire of the conflict, which began last December. Like the previous two peace deals, the third was quickly broken, proving that South Sudan's political settlements have little effect on the battlefield.

East African countries have stepped up threats that if warfare continues they will impose economic and political sanctions against the government of President Salva Kiir and rebel leader and former Vice President Riek Machar.

More fighting is expected in South Sudan as seasonal rains subside, say analysts. Fighting has been less intense the last several months during the country's annual rains.

Aguer said that government forces, known as the SPLA, expect rebels to launch more attacks on government positions and that despite Monday's violence the government is committed to a cessation of hostilities.

"This war must be stopped as quickly as possible because it is consuming our resources (and) it is killing innocent people," Aguer said.