By Frances Harrison
BBC correspondent in Colombo
The United Nations children's agency, Unicef, has fiercely criticised Tamil Tiger rebels for recent child conscription in Sri Lanka.
There was much media interest in the 50 children freed by rebels on Friday
As many as 23 children were abducted at the weekend by the rebels, according to reports from the small town of Valachchenai in the east of the island.
The abductions came just hours after the Tigers inaugurated a programme with Unicef on Friday to return child soldiers to their families.
Unicef said child recruitment by the Tigers was "completely unacceptable".
A statement said the agency had verified a number of cases of forcible child recruitment by the Tamil Tigers in the last few days.
But it added that the number of cases was not the issue - the abduction of even a single child was a serious violation.
Unicef pointed out that continued child recruitment undermined the rebels' stated commitment to demobilise child soldiers and it called for the immediate release of those abducted.
On Monday, hundreds of schoolchildren in Valachchenai staged an unprecedented protest against the abduction of their friends by the Tamil Tigers - sitting on the road and blocking the traffic.
The protest has continued for a second day, but is now confined to a handful of schoolchildren inside their compound.
Many parents are terrified of coming forward to the police or truce monitors and making a formal complaint.
Even local journalists are frightened of the rebels' reaction if they report the story.
The international ceasefire monitors are intervening to try and secure the release of the children, but their workers are increasingly being told by the Tigers not to report cases of child recruitment.
It's clear the rebels are sensitive to the negative publicity they get from underage recruitment, but not to the issue at the heart of it.