Just over half of 11-year-olds - 57 per cent - reached the expected level in reading, writing and maths in 2005, according to new government figures.
The figure was released in response to a Conservative request.
Although 84 per cent of pupils got level 4 in reading, 63 per cent in writing and 75 per cent did so in maths this year, just 57 per cent reached level 4 in all three.
In 1997, 43 per cent of pupils reached level 4 in reading, writing and maths. Nick Gibb, Conservative education spokesman, said that failure to publish the figure for reading, writing and maths gave the impression that pupils were doing better than they are.
He said: "Instead of a debate about the problems, the Government is creating a culture of complacency."
He criticised the Department for Education and Skills for not publishing the figure until asked.
A Department for Education and Skills spokesperson said the figure was not published because it did not relate directly to government's targets.
He said: "Government targets are for English and maths. There has been no suppression of figures."
Edward Davey, Liberal Democrat education spokesman, said: "Many children must master basic listening and speaking skills before they can improve reading and writing. Labour's narrow-minded policies fail to address this.
We need a new approach including smaller class sizes and a focus on talking and listening when children first begin school."