Numbers of primary pupils taking part in artistic activities after school have fallen by a third since the general election, according to a new Labour analysis of official figures.
And the figures show a widening gap between the participation of white children and those from black and ethnic minority backgrounds in after-school music, drama and dance classes.
Shadow culture secretary Harriet Harman said blame for the fall in cultural participation should be placed "fairly and squarely" at the door of the coalition Government, accusing former education secretary Michael Gove of "devaluing creativity" in schools.
Labour's analysis of the Department of Culture, Media and Sport's Taking Part survey showed that the percentage of primary children taking part in after-school music activities had fallen from 55% to 36% between 2009/10 and 2012/13, while numbers taking part in theatre and drama fell from 49% to 33% and in dance from 45% to 29% over the same period.
The slump in cultural and artistic activities among ethnic minority children was even more marked, with participation in music falling by 44%, in drama by 41% and in dance by 51% over the period.
The gap in participation between white and ethnic minority children grew from 3.4 to 10.5 percentage points in dance activities, from 6.4 to 8.9 points in drama and from 4.9 to 18.8 points in arts and crafts, said Ms Harman.
While children from ethnic minority backgrounds were 5.1% more likely than white children to take part in music outside school in 2009/10, they were 3.4% less likely by 2012/13.
Ms Harman said: "Taking part in art and culture is a vital part of a child's education and helps them develop their full potential
"This is important both at school and in after-school activities - whether it's dance, drama or music. But we are seeing a serious fall in the amount of art and culture that children are able to take part in.
"The blame for this lies fairly and squarely at the door of this Government. They don't understand the importance of the arts and their role to extend opportunities to every child.
"Michael Gove devalued creativity in schools and many local arts organisations who would provide out-of-school activity for young people have lost support because of the Government cuts to local councils. And more than a third of local authorities have reported a drop in after-school clubs since the elections.
"The widening gap between white and black and minority ethnic children is very worrying. It is every child's right to explore their artistic and creative potential - and that shouldn't depend on your race. These figures should be a wake-up call to the Government.
"Labour is committed to opportunity for every child to experience and participate in the arts. We will get Ofsted to check that every school is providing arts and cultural opportunities. We will use our plans for after-school clubs to give primary school children creative activities and get more local and national arts organisations involved so young people get access to the arts. We will ensure that arts organisations funded by the Arts Council extend opportunities to young people."
A Department for Education spokesman said: "It is nonsense to suggest we do not promote the arts either inside or outside school.
"We are determined to help every child develop their creativity. That is why we have invested £340 million to support music and cultural education that will help children to enjoy the arts.
"In the last month alone, we have cut red tape that restricted after-school drama performances and announced an £18 million funding boost for music education. The extra funding will mean thousands more disadvantaged pupils will have access to instruments."
The Department highlighted the £75 million music hub scheme set up in 2012 as part of the National Plan for Music Education, which in its first year gave nearly 500,000 children the opportunity to learn an instrument, as well as working with almost 15,000 school choirs, orchestras and bands.