JUBA (Reuters) - Fighting spreading along Sudan's new southern border could develop into a coordinated insurgency and encourage efforts to mount a political challenge to President Omar Hassan al-Bashir.
Clashes broke out earlier this month between the army and rebels loyal to Sudan's opposition SPLM-N party in Blue Nile state, the third area along the border with the newly created South Sudan to explode into violence in recent months.
The Sudanese army is already fighting SPLM-N rebels in South Kordofan, an oil state west of Blue Nile. And the United Nations is enforcing a ceasefire in the disputed region of Abyei after Khartoum seized it in May.
"There's a new 'South' in the north of Sudan. From Blue Nile to Darfur, people are seeking the restructuring of the centre," Yasir Arman, secretary general of the SPLM-N, told Reuters.
"This will put an end to Bashir's regime," he said.
Apart from South Kordofan and Blue Nile, dissent is simmering in other regions such as Darfur and east Sudan, a neglected region which has seen an insurgency in the past and where opposition groups demand more development.
Analysts say instead of seeking political compromise, Khartoum is counting on the military to crush rebellions and wants to placate hardliners in the army who see the loss of the south as a humiliation.
Bashir has replaced the SPLM-N's elected governor of Blue Nile, Malik Agar, with a temporary military leader and imposed a state of emergency.
The government blames the SPLM-N for the fighting and offers fighters who surrender the opportunity to become integrated into the regular army. It says the SPLM-N is an illegal party.
Some analysts say the fighting could push Agar, a popular SPLM-N leader who has built good working relations with Bashir's party since the 2005 peace deal, firmly away from resuming talks with Khartoum.
"Khartoum believes that the only way it can survive is by cracking down, but I think that could backfire. There's a possibility that this could fuse opposition factions," said Harry Verhoeven, a PhD candidate at Oxford University focussing on Sudan.
With much wealth and power concentrated in the hands of a few families in Khartoum, Sudan has faced insurgencies and armed opposition on its peripheries since independence from Britain in 1956.
While foreign investment has been on the rise since the 2005 peace agreement ended decades of civil war with the south, little has been done to develop infrastructure beyond the capital and central Sudan, which is fuelling anger elsewhere.
The government is building a huge new airport for Khartoum, but the capital of Blue Nile state, Damazin, has only a tiny airport, for example.
If the fighting continues to spread in a sustained way, it will put significant financial pressure on Bashir. Khartoum faces budget problems after losing 75 percent of its oil production when South Sudan became independent in July.
The SPLM party split into north and south along with the country itself earlier this year. The northern party now says it is looking to team up with rebels in the western region of Darfur, scene of an almost decade-long insurgency, on both a political and military level.
"We are going to have a political and military umbrella," the SPLM-N's Arman said.
He said SPLM-N was about to sign an alliance with the Sudan Liberation Movement (SLM) and Justice and Equality Movement (JEM), two Darfur rebel groups which have some historical ties with southern-allied opposition.
He said he envisions a group with a single leader which would later include "all other opposition political forces."
Analysts say such an alliance could pose a threat since the SPLM-N in South Kordofan and Blue Nile has several thousand troops and some military hardware left over from the civil war.
"The combination of extensive (combat) experience and regional network of the SPLM-N with the ongoing ability of the SLM and JEM to hold ground and maintain pressure in Darfur suggests that such an alliance has considerable military potential that could change the dynamics of politics in north Sudan," said Sharath Srinivasan, director of the Centre of Governance and Human Rights at the University of Cambridge.
JEM spokesman el-Tahir el-Faki said an agreement would be inked in the next few weeks.
"The first process was the formation of a political and military process. The next step is discussing how that framework will work," El Faki said.
Analysts say the SPLM-N would be a fit for Darfur rebels who are searching for new allies after the fall of Libya's Muammar Gaddafi, who gave them support and allowed the use of his territory.
"It's very clear that the SPLM-N have no other choice than mobilising their constituents for a popular uprising," said Fouad Hikmat at the International Crisis Group.
"An alliance would allow their forces to be more dynamic. I think it could be beyond rhetoric. It could go from an alliance to a joint command and create a wider opposition in the north but only time will tell if they can turn that into reality," he said.
Magdi El Gizouli, a fellow at the Rift Valley Institute, said the success of the planned alliance would depend whether it got any significant backing from abroad.
"Politically it's good because it sounds like there's a ring of rebellions in a big alliance. But militarily, they can't link all these fronts, not with the number of troops that they have," Gizouli said.
"This is going to be a long war," he said.
Western powers are pressuring South Sudan to stay out of the fighting. Analysts say its army, the SPLA, might have some ties with fighters on the ground but Juba denies it supports them.
"With the historic relationship there it's a temptation (to interfere) and it's one we want them to resist because... they are in a position to encourage the peace process," U.S. Special Sudan envoy Princeton Lyman said last week in Khartoum.
To ease tensions in the poorly marked joint border area, Khartoum and Juba agreed to withdraw their forces from Abyei which both sides claim, the U.N. said last week.
"These offensives in Abyei, South Kordofan and Blue Nile are a manifestation of a regime that is worried about their future," said Roger Middleton at Chatham House.
"The main threat is no longer just in Darfur. I don't know if they have the military capability to walk into Khartoum, but they might not need to. If they can keep the government tied down then it opens the possibility that political opposition can take the advantage through a popular uprising in Khartoum or a coup," he said.