The Tamilnet.com website said the four youths were abducted Tuesday while working on a road construction project to supplement family income.
The incident came a day after a top United Nations official accused Sri Lankan government forces of recruiting child soldiers on behalf of an allied paramilitary group also fighting Tamil Tiger rebels.
"The parents of the abducted youths have lodged complaints with Eravur (township) Police and the International Committee of the Red Cross (ICRC)," the Tamilnet said.
Spokesman Davide Vignati neither confirmed nor denied the ICRC had received the complaints.
President Mahinda Rajapakse's office said Tuesday authorities would investigate charges made by special advisor to the UN Representative for Children and Armed Conflict, Allan Rock.
It is the first time the UN has made such a charge against the government.
The Tamil Tigers have long been under fire for using children as soldiers in the separatist war.
The investigation came despite th