Some 170 people have fled rebel-controlled areas in northern Sri Lanka as fresh fighting erupted across several fronts, the military said on Saturday.
It said the 170 men, women and children had sought shelter in government-controlled areas in the north on Friday.
The International Committee of the Red Cross on Friday warned of a "massive displacement" of civilians, many of whom had already been forced to move numerous times.
"Tens of thousands of displaced civilians are concentrated in an area so small that there are serious concerns for their physical safety and living conditions, in particular in terms of hygiene," ICRC said.
Troops, backed by helicopter gunships, targeted rebels positions in the northern area of Dharmapuram on Friday, inflicting heavy casualties on the Tamil Tigers, the army said. It said a few soldiers were injured.
There was no immediate comment from the Liberation Tigers of Tamil Eelam (LTTE), but the pro-rebel Tamilnet.com website said 51 soldiers were killed in Friday's fighting in Dharmapuram.
"Fifty-one soldiers were killed and 150 troops sustained injuries in the confrontation that lasted for 14 hours from the early hours of Friday," Tamilnet said. It gave no rebel casualties.
Releasing pictures, the website also said LTTE fighters seized weapons after fighting ended.
A massive assault by Sri Lankan troops has left the Tigers cornered in their military stronghold in the northeastern coastal district of Mullaittivu.
Sri Lanka has poured a record 1.7 billion dollars into this year's war effort as troops push to eject the Tigers from their last stronghold in the jungle and lagoon district around Mullaittivu.
Tens of thousands of people have been killed since the Tamils launched their struggle for a separate homeland in 1972 in the Sinhalese-majority island.