JUBA (Reuters) - At least 165 people have been killed in the past week in fighting between south Sudan's army and militia, the army said on Monday, part of a wave of violence in the territory ahead of its independence in July. Forces loyal to two renegade army commanders fought the southern army (SPLA) in Jonglei and Unity states, killing soldiers, rebels, northern tribesman and civilians, SPLA spokesman Malaak Ayuen said. South Sudanese voted in January to separate from the north, which will split Africa's largest nation in July. The poll was promised in a 2005 peace deal that ended decades of civil war. Analysts say the oil-producing south could become a failed state after independence and destabilise the whole region. This year the SPLA has been at war with at least seven rebel militia, while the region is racked by traditional tribal conflicts and faces routine raids in its west from Uganda's Lord's Resistance Army rebels, the United Nations says. The violence in nine of the south's 10 states has killed more than 800 people - excluding those who died in the last two weeks - and displaced nearly 100,000 people, it said. Ayuen said an offensive in Unity state by renegade SPLA officer Peter Gadet since Tuesday has killed 101 people. "In the fighting in Unity state, we have lost 26 SPLA soldiers and at least 70 rebels have been killed, probably more," he said, adding the figures did not include a clash on Sunday when the SPLA pursued the rebels towards the border with the north. Three women and two children were killed after being caught in the crossfire, while the other dead were fighters, he said. The semi-autonomous southern government accuses Khartoum of supporting and mobilising the militias against Juba to create instability and keep the south weak and reliant on the north's oil infra structure. Khartoum denies the allegation. Some 75 percent of Sudan's 500,000 bpd oil production comes from the south but the refineries and port are in the north. Gadet's rebels say they are fighting to overthrow the southern government, which they say is corrupt and neglects tribal minorities and rural communities. "We are still on the offensive, we are defeating the SPLA in Unity state. We have captured 19 SPLA soldiers and killed many. We don't know how many exactly but it is a very big number," Gadet's spokesman Bol Gatkouth told Reuters on Monday. The top U.N. humanitarian official in Sudan Georg Charpentier in a statement on Monday expressed concern that two staff members from the International Organisation for Migration (IOM) were missing after the SPLA commandeered their vehicles and forced them to drive into an active conflict area in Unity. Oil production in the state was disrupted by the violence, according to state officials, who said they first expelled then re-admitted northern Sudanese workers to oil areas, underscoring the threat insecurity poses to the economy. In Jonglei, the SPLA clashed on Saturday with forces loyal to renegade commander Gabriel Tang, killing 64, Ayuen said. "The SPLA lost seven soldiers and 57 rebels were killed," Ayuen said, adding Tang had now surrendered along with at least 1,300 fighters. It was not clear whether Tang would be granted an amnesty the president has offered previously to all rebels. Ayuen said civilian casualties were low in Jonglei because the fighting had not been in residential areas, but officials in nearby Malakal reported dozens of wounded civilians. Both the SPLA and rebel militia have been accused of human rights violations in the ongoing crisis, which the SPLA denies.