KHARTOUM, Dec. 21 (Xinhua) -- South Sudan's army on Saturday said it was advancing under an air cover towards Jonglei state's strategic town of Bor that has been seized by forces loyal to a sacked vice president.
"The army is rapidly advancing towards Bor town, with an air cover of military helicopters," a military source in South Sudan told Xinhua by phone.
"The army is trying to avoid clashes in populated areas, while the other party uses civilians as human shields," the source added.
Earlier, forces loyal to former Vice President Riek Machar announced that they had taken control of Bor and its main military base after driving the forces loyal to President Salva Kiir Mayardit out of it.
Furthermore, the Nuer tribe-dominated forces reportedly announced that they seized the oil-producing Unity state and appointed a military governor for it.
However, South Sudan army's spokesman Philip Aguer told the media that Unity state is still under the control of the central government, but admitted that there were clashes in Bantio, the capital of the state.
Violent clashes erupted in South Sudan on Sunday between two military factions, one descending from the Dinka tribe to which Kiir belongs, and the other descending from the Nuer tribe to which Machar, who is accused of plotting to topple the government, belongs.