Sudan's government plans to increase military assistance to rebels in South Sudan, which could prolong the south's civil war and return the region to a wider conflict, according to a leaked document.

Sudan will provide tanks and artillery and share intelligence with rebels fighting South Sudan's government, according to the minutes of a high-level meeting of security and military officials in Khartoum, that a top American expert on Sudan has concluded are real.

South Sudan — which broke away from Sudan in 2011 after a peaceful vote for independence — has had an internal conflict since last December between supporters of the government and former Vice President Riek Machar. Thousands have been killed and some 1.7 million people displaced. Peace talks are ongoing but fighting continues.

The leaked minutes say that Machar and two commanders requested advanced weapons and training.

"Our reply was that we have no objection, provided that we agree on a common objective," said 1st Lt. Gen. Hashim Abdalla Mohammed, Chief of Joint General Staff in the minutes. Mohammed also talks about self-rule of South Sudan's Upper Nile region, where a lot of the country's oil is located.

But rebel leader Machar denied that Sudan was helping his side. "Khartoum is one of the mediators," Machar said in an interview with The Associated Press in August. "Khartoum is neutral."

A rebel spokesman, Brig. Lul Ruai Koang, on Friday also denied any links with Khartoum. Rebel fighters get their weapons by capturing them from government forces or soldiers who defect to the rebel side, said Koang.

However, outside analysts believe that the minutes of the meeting in Khartoum are real and show that Sudan still has designs on the south's oil.

Eric Reeves, a Sudan expert at Smith College in Northampton, Massachusetts, received the minutes — dated Sept. 1 from an Aug. 31 meeting — from a contact in Sudan and published them on the Internet. The document has since been making the rounds of Arabic readers and writers "and every single one I've been in touch with believes it to be authentic," Reeves said.

Reeves said any military assistance to Machar's rebels by Sudan when fighting resumes in December — after the end of the rainy season — "will be exceedingly violent and will horribly exacerbate the humanitarian crisis." Aid experts say South Sudan faces severe hunger and could fall into famine next year.

There is "increasing evidence" of Sudan's backing for South Sudan's rebels, including allowing the rebels safe haven in Sudanese territory, the Small Arms Survey, a publication by the Geneva-based Graduate Institute of International and Development Studies, wrote this week. It notes that South Sudan's government also believes Sudan is aiding the rebels, though Sudan's government denies the allegation.

Africa Confidential, an in-depth magazine focusing on Africa, concluded the documents are authentic after contacting current and former Sudan politicians.