Syria conflict has reached new levels of brutality - UN

syria's war has reached "new levels of brutality", the UN says, with evidence of fresh suspected massacres, sieges and violations of children's rights.

children have been taken hostage, forced to watch torture and even participate in beheadings, it says; others have been killed while fighting.

It says it suspects there are "reasonable grounds" to believe chemical weapons have been deployed.

It urges foreign powers not to increase the availability of arms in Syria.