Hundreds of Ugandan rebels including their deputy commander have gathered at two locations as part of a truce signed with the government three weeks ago, the chief mediator of peace talks said on Monday, according to Reuters. The presence of Lord's Resistance Army (LRA) deputy commander Vincent Otti is seen as a major boost to efforts to end one of Africa's longest and most vicious civil wars. "They have shown up in the western assembly point in Ri-Kwangba. They have also shown up in Owiny-ki-Bul," southern Sudan's Vice President Riek Machar told reporters in the regional capital Juba. "It is big progress that they have accepted to go to the assembly areas." The LRA fighters who have arrived at Ri-Kwangba, near the border with eastern Democratic Republic of Congo (DRC), include Otti, Machar said. LRA leader Joseph Kony was not far behind, he added. "Vincent is definitely there, behind the lines Joseph himself is there," Machar said in the southern capital Juba. He was unable to give exact figures but estimated that 400 guerrillas had gathered in Owiny-ki-Bul, east of the Nile in Sudan, with a bigger number in Ri-Kwangba. Less than a week ago, Otti -- one of five LRA leaders wanted for war crimes by the International Criminal Court (ICC) -- said his fighters would stay in the bush unless the world court dropped its arrest warrants. Machar said Otti had given clear instructions for the forces to trek to the two assembly areas where they will be fed and protected by southern Sudanese forces, but the Ugandan rebels had been delayed by concerns that some of the areas were mined. --More