Rasiah Ilanthiraiyan, Tamil Tiger military spokesman, denied any casualties and said the Tigers had killed 10 government soldiers who had launched a small attack in the restive Vavuniya district.
"It must be within 10 and I'm not sure, but it's not more than 10," Ilanthiraiyan said, referring to the number of government soldiers' bodies that had been found.
The military and Tamil Tiger claims could not be independently verified.
On Thursday and Friday, the majority Sinhalese and ethnic minority Tamils will both celebrate the New Year, and the government has warned the public to be vigilant for possible attempts by the Tamil Tigers to disrupt festivities.
The two-decade war has killed about 68,000 troops, rebels and civilians. More than 4,000 people have died in the past 15 months alone.