The bullets were found when 13 students were being checked for tuberculosis, Jaffna’s district tuberculosis officer, Dr S Jamunanantha said.
Most of the students were aged between 10 and 18 years. Until recently they were housed in camps in Vavuniya.
Tens of thousands of people have now left camps where they had been detained since May.
Those remaining were recently granted freedom of movement.
Sri Lanka’s army defeated Tamil Tiger rebels in May 2009 after a 26-year conflict.
‘Bullets in bodies’
The students had been displaced from their homes in the Wanni region during the conflict.
“A few students said they are having bullets in their bodies. We immediately conducted an x-ray examination. We found bullets and shrapnel,” Dr Jamunanantha said.
They have now been referred to Jaffna’s teaching hospital for surgery.
But doctors say they fear that there may be more undetected cases of bullets and shrapnel lodged inside refugees.
“Many of them, who were injured during the final months of war, might have got only emergency first aid in the war zone.
“So it is highly possible some of them may still have a bullet or shrapnel in their bodies. We are urging them to come forward for an x-ray examination,” said Dr Jamunanantha.
Although doctors say the presence of bullets may not cause immediate health problems, it could be problematic in the long term, Dr Jamunanantha says.
The authorities say they are hopeful that more people will come forward for screening.
During the final phase of Sri Lanka’s conflict a number of civilians were injured in the heavy fighting between Tamil Tiger rebels and Sri Lanka’s army.
Many could only receive emergency care from a makeshift hospital in the war zone.
The number of people who were killed and injured during the war is still disputed.
Earlier, the UN said it believed about 6,500 civilians died in the conflict, but later the organisation said there were no confirmed estimates of civilian casualties.