By Jeremy Clarke
JUBA, Sudan (Reuters) - At least 20 soldiers were killed in a clash between south Sudan's army and rebel militia fighters, the army said on Wednesday, the latest violence to unsettle the region ahead of its independence in July.
Sudan's oil-producing south voted to separate from the north in a January referendum promised under a 2005 peace accord that ended decades of civil war.
The underdeveloped region, the source of most of Sudan's 500,000 barrels per day of oil, has been beset by violence since the vote.
Hundreds have died in tribal fighting and clashes between soldiers from the southern army (SPLA) and at least seven bands of renegade fighters in the territory, according to the United Nations.
Analysts have warned any further deterioration in the south could destabilize the whole region. South Sudan's neighbours include Kenya, Uganda and Ethiopia.
Twenty southern army soldiers were killed on Tuesday in a clash with fighters loyal to Peter Gadet, a former SPLA officer who rebelled this month, the military said.
"They (the rebels) overran a village in Mayom county. They burned it to the ground before the SPLA chased them off," said southern army spokesman Philip Aguer.
Two drivers were also killed when two civilian trucks hit landmines in the same county, Aguer said.
The United Nations has said more than 800 people have died in the violence in south Sudan this year.
Southern leaders have accused their former civil war foes in the north of arming the renegades to try and destabilize the region and keep control of its oil. Khartoum denies the accusation.
Renegade fighters have accused the south's government of corruption and crackdowns on opposition supporters, charges denied in the southern capital Juba.
Rights group Human Rights Watch (HRW) has accused both SPLA and rebel fighters of human rights violations during a battle in Upper Nile State in March
Aguer dismissed the allegations against the SPLA.
The south has fought the north for all but a few years since 1955 over differences in religion, ideology, ethnicity and oil. The conflict has claimed an estimated two million lives.
(Editing by Deepa Babington and Andrew Heavens)