The Sri Lankan military and Tamil Tiger rebel leaders are battling for control of what is now a rebel enclave in the east of the country. The fighting comes as more than half of the international monitors in Sri Lanka to oversee a battered ceasefire have left because of an ultimatum by the rebels.
Senior Sri Lankan military officials say they expect to take control of Sampur in a matter of days. The rebel enclave is south of Trincomalee, a key port city controlled by the government in the east of the country.
Tamil Tiger leaders have dismissed the government's threat to take Sampur. They have also warned the battle could mean the end of a tattered ceasefire the two sides signed in 2002, in an effort to end two decades of civil war waged over the rebels' demand for a separate homeland.
Norway brokered that truce, which saw the deployment of dozens of European ceasefire monitors across the country.
But Friday marked a deadline issued by the Tamil Tigers for more than half of the 57 ceasefire monitors to leave Sri Lanka - and the monitors have complied. The rebels demanded observers from Denmark, Finland and Sweden withdraw, after the European Union labeled the Tamil Tigers a terrorist organization in May.
If the observers from the Sri Lanka Monitoring Mission, or SLMM, stayed, the rebels said, they could not guarantee their safety. Just 20 monitors from Iceland and Norway remain.
The fight over Sampur is the latest clash in more than six weeks of renewed fighting that some estimate has claimed a thousand lives, and driven more than 200,000 from their homes. The northern Jaffna peninsula has seen very heavy fighting. So has Muttur, a town bordering the Sampur enclave.
Controversy surrounding a brutal incident in Muttur appears to have soured relations between the SLMM and the Sri Lankan government.
The SLMM has blamed government forces for the massacre of 17 aid workers from the French organization, Action Against Hunger. Most of those killed were ethnic Tamils, and witnesses say they were found face down in the group's compound, having been shot in the back of the head.
Ulf Henricsson, the head of the SLMM, says even before the killings in Muttur the government restricted SLMM access to the town, saying it was too dangerous.
"We tried for several days to come into Muttur and monitor it. It was not allowed to come in, always due to security reasons. That's the same time, it was possible to send journalists in to Muttur, so I don't really believe in the motives," said Henricsson.
The Sri Lankan government has vehemently denied its forces killed the aid workers. It has also criticized the SLMM for making the statement before the completion of a government investigation into the killings.