Kampala, Uganda: South Sudan’s military on Friday accused the Sudanese government of aiding a new rebel offensive in the southern country where oil fields are now threatened by fresh fighting.

The recent defection in South Sudan’s Upper Nile state of a key general to the rebel side was likely tied to incentives from Sudan’s government, including weapons and ammunition, South Sudanese military spokesman Col. Philip Aguer told The Associated Press. The general, Johnson Oloni, had previously been a member of the government’s military alliance against rebel forces loyal to former South Sudan Vice President Riek Machar, whose fighters control some parts of South Sudan and are pushing to seize oil fields.

“Sudan doesn’t just have a hand in the fighting, it has both hands in this,” Aguer said by phone from the South Sudanese capital of Juba.

It’s not the first time South Sudan is accusing its neighbor of supporting rebels, charges routinely denied by Sudan’s government in Khartoum.

Fighting has recently escalated in the states of Unity and Upper Nile, where the last remaining functional fields are threatened by rebels who said this week their goal is to seize the oil hub of Paloch.

South Sudan’s military later said the rebels had been repulsed but acknowledged fighting is ongoing in nearby counties. If Paloch were to fall to the rebels, it would be a disaster for President Salva Kiir’s government, which depends heavily on oil revenues to pay its bills.

Thousands of civilians are trapped in the fighting, many of them fleeing to unsanitary swamps as aid workers shut down their facilities and pull out.

Doctors Without Borders described an “alarming humanitarian situation,” saying masses of people are hiding in the bush and that the “lack of access to the injured and displaced puts the lives of many South Sudanese at critical risk.”

Amnesty International said Thursday it had spoken to witnesses in Unity state who said government troops have been burning villages, abducting children and raping women in an ongoing offensive against rebels.

Peace talks between the warring factions have repeatedly collapsed.