Jonny Donovan BBC reporter in Madagascar

Since last weekend, the lush green Sava region on Madagascar's north-eastern shores has become the latest battleground in the ongoing struggle for power between political rivals Didier Ratsiraka and Marc Ravalomanana.

Since Ravalomanana's soldiers arrived, we have finally felt secure

Local resident, Sava region

Last Saturday, forces loyal to the newly sworn in president wrested control of the town and airport of Sambava from Ratsiraka's militia in what is the Ravalomanana camp's largest military offensive to date.

Following a number of skirmishes in the vanilla-rich environs north of Sambava, the Ravalomanana offensive has managed to push Ratsiraka forces to beyond the Bemarivo bridge some twenty kilometres (12 miles) out of town.

Superior weapons?

Lack of fuel threatens the local power supply

'We don't know exactly how strong the Ratsiraka forces are,' said one commander scanning the opposite side of the river with his binoculars, 'But we fear they may have superior weapons'.

In the latest clash between the two sides on Thursday afternoon, say pro-Ravalomanana paramilitary, two truckloads of pro-Ratsiraka soldiers engaged the Ravalomanana front line in gunfire around the bridge.

This allowed some 20 pro-Ratsiraka militia to cross into Ravalomana-controlled territory further downstream.

Security fears

So far, pro-Ravalomanana paramilitaries say a total of 12 people have been killed in sporadic fighting and many others injured, including some civilians.

The Sava region is one of the most remote and inaccessible parts of the country

Mr Ravalomanana's forces - who call themselves 'The army of National Liberation' - justify the attack there as both a means to secure control of the valuable vanilla harvest due to start shortly, and a way of liberating locals from atrocities allegedly committed by militia controlled by elements in the Ratsiraka camp.

The Bemarivo bridge separates opposing forces

"Since the Ravalomanana soldiers arrived we have finally felt secure," said one local resident. "It was terrible before, you cannot imagine how much fear we lived under."

According to independent sources in the region and human rights groups, armed gangs of militia under the control of a notorious local pro-Ratsiraka deputy named Madame Soalima have kept the town of Sambava in a state of constant terror since the beginning of the political crisis.

"We hope to take the fight all the way to the provincial capital of Diego Suarez, and eventually secure the entire northern province,' said one pro-Ravalomanana commander, whose force is made up largely of ex-military who have re-volunteered for active service.

But there are many more immediate obstacles in the way of a full offensive into the north.

Threat to facilities

The manager of the state electricity company in the town of Sambava predicted a complete power failure on Saturday morning unless more diesel was found immediately to power the generators.

No power could put patients' vital drugs at risk

"Sambava's strategic reserves of diesel are almost dry, and the only place where diesel can be unloaded by boat is under Ratsiraka control to the north."

A loss of power would also immobilise the local mobile phone network - the principle means of communication for the Ravalomanana forces in the region.

Equally worrying are the possible repercussions for people.

Doctors at the local hospital in Sambava fear the loss of refrigeration facilities should the electricity fail.

"We have 19 people who were recently operated upon and 40 others in the hospital. With no power we would be forced to throw away many of our refrigerated medicines," said one doctor.

With the only port town near Sambava capable of receiving fuel still well behind Ratsiraka lines, the long-time president's continuing monopoly on the island's remaining fuel supply may again prove to be a thorn in the side of the Ravalomanana camp's attempts to extend its power base into the provinces.