NAIROBI (Reuters) - Heavy fighting erupted on Friday in the South Sudanese town of Pagak near the border with Ethiopia when rebels launched an offensive against government forces, the rebels said.

Rebel spokesman Lam Paul Gabriel told Reuters that the rebels were seeking to regain Pagak, which was captured by government forces on Aug. 7.

“We decided to launch an attack on them because Pagak is our base. They took it from us and we want to take it back,” Gabriel said.

“We cannot say right now that we are in full control but we are going towards taking control.”

Dickson Gatluak Jock, a spokesman for the forces of South Sudan’s First Vice President Taban Deng Gai, confirmed that they were engaged in fighting.

“At 5:00 am, SPLA-IO forces (loyal to the Juba government) came under heavy fire (from the rebels) in Pagak ... Their main aim was to drive out our forces from the strategic town of Pagak,” he told Reuters.

South Sudan descended into civil war in 2013, only two years after it won independence, when President Salva Kiir fired his deputy, Riek Machar, unleashing a conflict that has since splintered along multiple ethnic lines.

Machar has been under house arrest in South Africa since December as regional leaders try to bring about an end to the conflict. The rebels fighting government forces in South Sudan remain loyal to Machar.

UNMISS, the U.N. peacekeeping force in South Sudan, told Reuters in an email the situation in Pagak was “extremely worrying” and urged all combatants to show restraint.