Child-trafficking is common in parts of West Africa

The children, some with open wounds, are being cared for by health-workers at a stadium in the Benin capital, Cotonou, AP news agency reports.

"We would break the stones, and the men would come to take them away in trucks," said a boy aged about 10.

Some 15,000 Benin children are thought to work in south-eastern Nigeria. Last month, 116 children were returned.

The children told United Nations officials that 13 of their companions had died in the past three months, worn out by smashing and carrying rocks and sleeping in the open without adequate food.

'Washed and dressed'

Nigerian federal police inspector-general Tafa Balogoun said the children had worked for more than a year in Nigeria's granite quarries.

They were returned to Benin by Nigerian police, under an agreement reached when Presidents Olusegun Obasanjo of Nigeria and Mathieu Kerekou of Benin in August.

"The children must be washed, dressed and allowed to rest a little before social workers can start interviewing them to find their parents and return them to their families," said Benin official Latoundji Lauriano.

The two countries will now begin inspections of Nigerian sites where trafficked Benin children may be working, Benin's Family Minister Massiyatou Lauriano told the AFP news agency.