NEAR KURMUK, Sudan (Reuters) - A convoy of white Toyota pick-up trucks and 4x4s, smeared with mud for camouflage, lurches off the road and hastily parks under the shade of some trees to the drone of a plane overhead.
Sudan Peoples' Liberation Army-North (SPLA-N) rebels, their vehicles bristling with rocket-propelled grenade launchers and Kalashnikov automatic weapons, leap off.
To cries of "Antonov," they cover the windscreens with blankets, crouch in the swaying chest-high grass and look up.
Seconds later, a white plane flies overhead, accompanied by the low growl of its engines. It circles for 10 minutes before dropping three or four bombs a mile (one-and-a-half km) away.
The SPLA-N rebels fought alongside southern Sudanese in a 22-year civil war which ended in a 2005 peace deal leading to the South's secession last July.
But the territory they fought for in South Kordofan and Blue Nile is just north of the new border, and so their battle with Sudanese President Omar Hassan al-Bashir, in power in Khartoum since 1989, has resumed.
The attacks aim to force civilians to flee their villages, severing local support for the guerilla fighters, rebels say, accusations the government denies.
Rights groups and analysts say the use of "indiscriminate bombing" by Soviet-made Antonovs would mirror tactics used by Khartoum in the restive regions of South Kordofan and Darfur.
"The civilians are their mothers, their wives, their beloved
ones," rebel leader Malik Agar told reporters on a trip to the region organised by rebels based in South Sudan, where the Sudan People's Liberation Movement is the main party.
"If you bomb them, then you scatter them all over the area. Then you will break the will of the fighters."
Huwa Jundi, like others this reporter spoke to on the trip, said she fled her home and now lives off wild plants and sorghum from vacant farms.
"When we hear the voice of the Antonov, we know it well, so we hide," she said.
Her family sleeps under a blue tarpaulin draped between trees, an hour's drive north of the rebel-held stronghold of Kurmuk.
Blue Nile state is home to thousands of rebels who fought with the south during the civil war and found themselves in north Sudan after the southern independence. Northern officials say they refused to disarm themselves before fighting broke out in September.
The U.N. High Commissioner for Refugees has said more than 27,500 people fled Blue Nile to Ethiopia in the last month, abandoning homes and farms weeks before the harvest starts.
"If you remove the civilians, you remove a base for supply to the fighters of the insurgency. That was the strategy of bombing Darfur before," said Faoud Hikmat, a Sudan analyst at the International Crisis Group.
"Denying food access is going to weaken the (SPLA-N's political arm) SPLM-N ... The government doesn't want international aid agencies to go in and start distributing food in South Kordofan and Blue Nile. There is no doubt that this is humanitarian politics," he added.
Khartoum dismisses such accounts, saying they are given by Agar's supporters to back his case. But analysts tell a different story.
"The bombing is completely ineffective militarily because the chances of hitting anything are so small. Virtually non-existent. There really isn't a strategy other than to scare everybody," Donatella Rovera, Sudan researcher at London-based Amnesty International human rights group told Reuters.
At the beginning of October, locals say a bomb killed half a dozen people in Maiyes, a village near Ethiopia's border.
Holding a piece of twisted iron shrapnel next to the churned earth around the crater, neighbour Mahmoud Abdanafi Jundi says the village buried the victims' bodies in one grave.
"When the bomb hit, the people in the house over there, three of them were killed. The people who were living here also died. A child over there was also killed," he said, gesturing to thatched huts that now lie empty.
Agar was sacked as governor of Blue Nile state when the fighting erupted and has set up a temporary command headquarters near Kurmuk, about 600 km (375 miles) southeast of Khartoum. He calls the camp his "backyard palace -- green, pleasant and beautiful."
A book by British journalist John Simpson, 'The Wars against Saddam', lies on his bedside table. Several satellite phones lie under his pillow.
Agar says he controls 80 percent of territory in Blue Nile and South Kordofan, and wants U.N. humanitarian corridors and safe zones for those displaced.
"Bashir is saying that he won't allow any (displacement) camps ... he won't allow any foreign (aid agencies) to intervene in Sudan, to render services to the people and denying access to the two areas," Agar said.
"This is clearly the way he is using food as a weapon," Agar says, in his military fatigues, surrounded by soldiers.
Khartoum rejects Agar's estimate that half a million people may be in need of humanitarian assistance in the state, and says it controls 90 percent of the land in Blue Nile and is providing services to 95 percent of its residents.
It blames rebels for sparking fighting that is causing any hardship but plays down any disruptions.
"Life right now in Blue Nile is normal as before," Rabie Abdelaty from Sudan's Information Ministry told Reuters by telephone.
The SPLM-N accuses Khartoum of having started the violence as part of a campaign to oppress the opposition. Khartoum has banned the party on the grounds that it is not registered.
At least 74 people have been killed and over 100 injured by Antonovs since the fighting started a month ago, Agar said. His figures could not be independently verified.
He said Bashir's government cannot be reformed and that he is forging closer alliances with insurgents in the troubled Darfur region of west Sudan others in the east. The aim, he said, was to launch a coordinated attack on Khartoum.
But he also wants the international community to press Bashir to resume talks to find a political solution, although he
has not elaborated much on his goals beyond reaching a ceasefire.
Khartoum has ruled out direct talks as well as negotiations involving a third party, a stalemate that suggests there is little chance of a quick end to the fighting.