Ethnic minority groups have joined condemnation of a primary school lesson in which children were ordered to line up according to their skin colour.

Year 6 pupils at Ryelands Primary School, in South Norwood, were told by teaching assistants to organise themselves "from lightest to darkest" during a class last week, allegedly leading to bullying.

Oasis Community Learning, which runs the school, defended the lesson, which it said had been intended to teach children about ethnic diversity.

But some parents branded it "highly inappropriate" and said it had led to one pupil being picked on due to the colour of their skin, while a prominent race relations campaigner has described it as "cack-handed and inept" and called on the school not to repeat the lesson.

The exercise involved about 30 children who were taking a lesson in the school's playground designed to prepare them for secondary school.

One child's mother, who asked not to be named, said: "Parents have told me children laughed at one child because he was 'the blackest' and arguing about who was darker and who was lighter, which is not something that you want to be happening in your school.

"I would be mortified if it was my child.

"I think it is highly inappropriate. Parents have complained but the school did not apologise for it, they tried to explain it away."

Oasis, which took over the running of the Albert Road school last week, said the lesson had been taken by two mixed-race teaching assistants who encouraged children to "talk about differences in a positive way".

A spokesman for the organisation, which sponsors six Croydon schools, said: "Inclusion is our raison d'etre and we are very committed to equality.

In this instance, it was about celebrated differences and saying it is OK to talk about them in a positive way but recognising we are all the same underneath.

"We fully support the teaching assistants that were involved but of course we are always willing to listen to feedback about how we do things in the future."

He added: "Had there been any children making inappropriate comments, they would have been picked up for that immediately."

But Lee Jasper, a race relations campaigner and the Respect Party's former Parliamentary candidate for Croydon North, described the exercise as "a cack-handed and inept way of delivering a very important subject". 

He said: "Of course, one wants to teach children about the nature of multicultural societies and different cultures, but the way in which this lesson was delivered actually resulted in children becoming a target for bullying and harassment.

"While well-intended, it has caused no little distress and I think the school needs to rethink its lesson plan on an inclusive multicultural democracy and have a much more considered approach to providing these important citizenship lessons to youngsters.

"It caused more damage than the good it was intended to do. To that extent, I think the school has to have pause to reflect about make sure they get it right for the following term and the remainder of the academic year."

Croydon Guardian: Lee Jasper speaking at the launch of Harrow Black History season

Lee Jasper, who stood for Respect in the 2012 Croydon North

Nero Ughwujabo, chief executive of Croydon Black and Ethnic Minority Forum, said there were "more sensible ways of teaching children about diversity". 

He added: "What is reported to have transpired in terms of young pupils being picked on is likely to come out of this blunt approach.

"Whilst we accept that the school would want to promote diversity and address those sort of issues, there could be more appropriate ways to do so.

"There are risks attached to this sort of gimmicky approach. I can't see the benefit of asking them to line up. And then what? What is the issue? Is it just pointing out that there are different shades?

"Inevitably it would inspire laughter and derision instead of learning about diversity."

He added: "It is not an approach I have ever heard of. It is quite extraordinary where they have got that idea from."

Ofsted last month branded Ryelands inadequate following an inspection in February, with teaching, pupil achievement and leadership and management all awarded the worst possible rating.