Despite an attempt by regional leaders to broker a truce, South Sudan’s army battled an ethnic militia on Sunday that appeared not to be allied to the country’s renegade former vice president, Riek Machar.

The feared “White Army,” made up of young Nuer fighters who dust their bodies with ash, clashed with government troops in the vicinity of Bor, a town north of the capital Juma from which rebels had been driven out last week.

A rebel spokesman denied that the White Army was controlled by Machar, a Nuer, whose followers oppose President Salva Kiir, a Dinka. The news agency Reuters reported that the militia had dwindled in numbers after Nuer elders and politicians persuaded members to abandon their march on Bor.

Bor was the site of an ethnic massacre of some thousand Dinka at the hands of Nuer fighters, led by Machar, in 1991. He apologized for his part in the atrocity last year.

Ethiopian prime minister Hailemariam Desalegn and Kenyan president Uhuru Kenyatta held a round of talks with Kiir before the weekend but with Machar’s whereabouts unknown and the rebels apparently divided, their hopes of ending the hostilities through negotiations may prove elusive.

Two weeks of fighting are believed to have left at least 1,000 dead and split the landlocked country barely two years after it won independence from Sudan.