In a report the organisation urges the UK to repeal laws which require 'broadly Christian' worship, and for pupils to be given the right to withdraw from any form of religious worship in schools.
The report was produced by a group of "independent experts" of "high moral character."
Speaking to Premier, Jay Harman from the British Humanist Association said: "It's an affront to the rights of parents and children for all the reasons that the UN said.
"It doesn't allow them to exercise their freedom of religion and belief, the opt out that's in place isn't sufficient and we think it's long past time that the requirement was scrapped.
The report said: "The Committee is concerned that pupils are required by law to take part in a daily religious worship which is 'wholly or mainly of a broadly Christian character' in publicly funded schools in England and Wales, and that children do not have the right to withdraw from such worship without parental permission before entering the sixth form."
It discusses two UK countries in particular: "In Northern Ireland and Scotland, children do not have right to withdraw from collective worship without parental permission.
"The Committee recommends that the State party repeal legal provisions for compulsory attendance at collective worship in publicly funded schools and ensure that children can independently exercise the right to withdraw from religious worship at school."
Christian Conservative MP for Enfield Southgate David Burrowes told the Daily Telegraph newspaper it was "ludicrous and mad."
In the same report the UN also calls on schools to provide age-appropriate sex and reproductive health education in all schools, including Christian schools.
Listen to Premier's Marcus Jones speak to Jay Harman from the British Humanist Association here:
