MONTEVIDEO, March 13, 2008 (AFP) - UN-assisted childrens' rights groups Thursday demanded the immediate shutdown of a juvenile detention center outside Montevideo, saying young offenders are subjected to physical abuse and torture.

'Our final evaluations lead us to describe the situation as extremely serious, in view of the flagrant human rights violations,' Childrens' Rights Committee (CDN) director Luis Pedernera told AFP.

He said the CDN had asked the Uruguay government to close down Colonia Berro, a juvenile detention center 45 kilometers (28 miles) outside the Uruguayan capital housing 250-300 underage offenders.

A CDN investigaion found children at the center suffered abuses including group beatings, floor slammings, sodomizations with sticks, forced kneelings on gravel, head stuffings in toilets and letting insects crawl over their faces.

The children were kept in 'forced lock down' 23 hours a day in crowded cells at the center, which lacks proper health care facilities, investigators said.

The abuses were included in a CDN report on Uruguayan juvenile detention centers drawn up with the help of Rosa Maria Ortiz, a member of the UN Committee on the Rights of the Child.