Thousands of civilians have fled their homes in eastern Sri Lanka because of heavy fighting between government troops and Tamil Tiger rebels.
Civilians say the army is launching an offensive
A BBC correspondent in Batticaloa says that 3,000 mostly Tamil civilians arrived in the town on Thursday.
Most came from the Paduvankarai area east of Batticaloa town, and said they were escaping heavy artillery fire.
The civilians said they believed troops were massing for a major offensive. The government denies the reports.
Correspondents say that troops backed by artillery and multi-barrel rocket fire are advancing towards Thoppigala, a key Tamil Tiger base in the east.
Military spokesman Prasad Samarasinghe told the BBC Sinhala's service no operation was taking place around Thoppigala.
He confirmed that more than 13,000 people had reached government-controlled territory but said they were fleeing because they feared the rebels would used them as "human shields".
Most of the troops are reported to have been deployed from Batticaloa district, backed by security forces in adjoining Ampara district.
"We have not had any reports of casualties," an officer in Ampara told the AFP news agency earlier.
"About 10,000 families in neighbouring areas have fled and sought shelter in government-held areas."
The head of the Tiger's political wing, SP Thamilselvan, told the pro-rebel website Tamilnet that the army had amassed military hardware in preparation for a major offensive towards the Mullaitivu area.
"The consequence of this will be a catastrophic bloodbath across Sri Lanka," he said.
The army denies any major operation is taking place
A Tamil Tiger statement on Thursday said that "continuous shelling" by the Sri Lankan armed forces in Batticaloa had escalated into "large scale attacks".
They accused the army of attacking at least four rebel camps, displacing thousands of civilians.
A BBC correspondent in the town of Batticaloa says that 5,000 civilians have arrived in the town over the last few days to escape the fighting.
In January, troops captured the eastern town of Vakarai from the Tamil Tigers after weeks of heavy fighting.
The government says that it wants to rid the eastern province of the rebels.
Thoppigala is believed to be one of their last bastions in Batticaloa and Ampara districts.