Senior officials at the Qualifications and Curriculum Authority are concerned about the dominant influence of external exams and tests on schools.

The regulator has suggested that teachers could have a bigger role in assessing their pupils' work, with less emphasis on external testing.

During the course of their school careers, children in England typically sit about 70 tests and exams.

Teachers have warned that the last year of primary school has become a "boot camp" for 11-year-olds who are drilled to get good results in national tests in order to boost their school's place in league tables.

Ken Boston, chief executive of the QCA, has written to ministers warning that "long standing issues" around league tables will have to be addressed.

In a letter to schools minister Lord Adonis, Dr Boston said: "There are long standing issues around the inclusion of all qualifications in performance tables, and the impact that those tables have on the curriculum and on the learning experience of young people.

"Some of those will need to be addressed as the qualifications market develops over the next few years."

In a separate letter, Dr Boston wrote to Alan Johnson, who was Education Secretary at the time, welcoming the Government's plans to pilot different ways of testing children.

Pupils in the 10 pilot areas will take tests as soon as they are ready, rather than only at the fixed ages of seven, 11 and 14.