South Sudan's army said on Monday it had retaken the strategic northeastern town of Malakal from rebels, the latest time the ruined state capital has swapped hands.
Rebels led by ex-government general Johnson Olony -- accused by aid agencies of forcibly recruiting hundreds of child soldiers -- seized Malakal, the state capital of Upper Nile, in late June.
The town is the gateway to the country's last remaining major oil fields and has been repeatedly fought over during the 18-month long conflict.
The army late Sunday launched an assault to retake the town.
"The rebels fled to different directions," army spokesman Philip Aguer told AFP Monday, saying the government was in "full control."
South Sudan's civil war began in December 2013 when President Salva Kiir accused his former deputy Riek Machar of planning a coup, setting off a cycle of retaliatory killings across the country that has split the poverty-stricken, landlocked country along ethnic lines.
Aguer also dismissed the rebel's claims to have shot down a helicopter gunship on Sunday as a "fabrication."
Thousands of Ugandan troops backed by helicopter gunships are fighting for Kiir.
Ugandan airforce spokesman Kiconco Tabaro said the rebels were "daydreaming" and no aircraft had been hit. "None has been shot at unless the rebels shot a ghost aircraft," Tabaro said.
Four years after South Sudan won its independence from Sudan, two-thirds of the country's 12 million people need aid, according to the UN, and one-sixth have fled their homes.
A UN report last week described horrific violence, with witnesses saying the army gang-raped girls and torched them alive in huts.