By Samanthi Dissanayake
BBC News website
The latest fighting in north-eastern Sri Lanka began as a dispute over water supplies in the district of Trincomalee.
A civilian injured in the shelling of Muttur town
The district, which includes the port town of Trincomalee, covers a long coastal strip of arable farmland and scrub jungle peppered with small villages.
The Sri Lankan government has overall control of the district but the rebels control pockets of coastline and some of the jungle in the interior.
The Maavilaru waterway snakes its way through jungle some 70km south of the port.
A sluice gate here is at the heart of the current fighting between the army and Tamil Tiger rebels.
'They just want to farm'
The Maavilaru sluice gate is five miles from the closest settlement. But the waterway it controls provides crucial irrigation for the farmers in surrounding areas.
The government says it began its offensive last week against the rebels because they are stopping water in the areas they control from reaching people in government-controlled areas.
The Tigers say local people closed the gate in a protest over government delays to improvements in the water system.
The area hosts a mixed population of Sinhalese, Tamils and Muslims who have lived together since the 1950s. There are some villages with mixed populations but most are segregated.
Nevertheless people co-exist in relative harmony and farmers of all ethnicities work together to manage the irrigation of their fields.
One source who knows the area and the irrigation system well, told the BBC News website: "Contrary to popular belief there is no real ethnic hatred. They just want to farm. These are people trying to disengage from either side and get on with their livelihoods."
The blocked waterway affects about 8,000 farmers. According to the source, if the situation is not resolved soon many Sinhalese farmers could lose their crop. Tamil and Muslim farmers would be spared only because they planted their seeds earlier.
The Tigers on parade - both sides say they do not want war
The conflict hits an already vulnerable group. Five of the last six seasons have been poor for the farmers in this area. The low price of rice combined with the high cost of fuel, labour and pesticide mean that few have made a profit.
But there are more critical concerns. The southern area served by the waterway has very little natural groundwater. That means that people who are now cut off from the Maavilaru waterway are deprived of their main water supply. Currently, water is being brought to them by tractor.
The only access to the sluice gate is along a long bund on an open paddy field surrounded by jungle.
"It is terrain which would be very easy to defend and very difficult to attack. There is nowhere to seek cover if attacked from the jungle, which is largely controlled by the Tamil Tigers," the source told the BBC.
The area is also heavily mined.
That all makes it extremely difficult for the Sri Lankan army to make headway in the area against the Tigers.
On Wednesday the Tigers attacked army camps north of the waterway, saying the move was in part to distract the estimated 3,000 troops from the waterway.
The fighting has also spread to the nearby town of Muttur where thousands of Muslims have been caught in the crossfire between the two warring sides.
The question is: Will this fighting remain relatively localised or lead to a resumption of all out civil war that both the government and the Tigers say they do not want?