Philip Pullman, Carol Ann Duffy, Michael Morpurgo and Ros Asquith attack the "growing domination of the school curriculum" by national tests."
The authors say that the concentration on test revision is deterring children from reading for pleasure as parents buy revision packs rather than books.
Alan Gibbons, the teacher and author, said: "It is extractitis. I believe good punctuation and good grammar should be developed in context. Parents buy revision packs rather than books. I believe books are more potent in genuinely raising literacy standards.
"National tests have squeezed storytelling in schools. Many junior schools have stopped having storytime at the end of the day." He said the tests were narrowing the whole notion of education.
"There is a very uniform view of what education is, that it is about getting a particular level."
A TES poll last year found that one in seven schools starts revision for the Year 6 national tests in the autumn term.
Alan Gibbons, 19 Letters, 21