Updated

A senior military official says 24 South Sudanese soldiers were killed in clashes with a militia group that the southern government accuses of subverting a disarmament campaign.

South Sudan army spokesman Col. Philip Aguer said Monday that an additional 12 soldiers were wounded and 17 are still missing from the Aug. 22 ambush of 200 South Sudanese troops who had been sent to quell alleged rebel activity in Jonglei State, the scene of a disarmament program that Human Rights Watch criticizes as too violent.

Aguer said the rebels are led by an elusive militant named Yau Yau and that they are backed by South Sudan's northern neighbor Sudan, which consistently denies similar allegations.

Relations between the two Sudans are tense, particularly along the border between the two countries.