Some primary school children are not mastering the three Rs

The measures announced by Chief Inspector of Education Christine Gilbert will target struggling schools.

Parents and pupils will also play a part. Any complaint made could trigger an investigation, said Ms Gilbert.

The new system would come into force from September 2009 and includes plans for inspections without warning.

Under current rules, schools are inspected every three years and receive two days' notice of a visit.

But under a shake-up, schools judged by inspectors to be satisfactory or inadequate would receive more regular visits, Ms Gilbert told a head teachers' conference in London.

About 45% of England's schools fall into this category and these would receive annual checks.

Even schools judged to be "good" but showing signs of slipping could receive "monitoring visits" every year or every term.

The best schools will be left for up to six years between inspections.

Ms Gilbert said the education watchdog would focus more on the "shocking" numbers of pupils who leave primary schools without mastering the three Rs.

She said: "If you are a satisfactory or a coasting school or a deteriorating school, or a school in difficulties, we will certainly be inspecting every three years but probably more regularly than that and probably more intensively than that.

"We are thinking about tailoring inspections much more."

Primaries penalised

Ms Gilbert told the National Academies Conference that the views of pupils and their parents would play a bigger part in Ofsted's work under the plans.

Complaints from parents about a school judged to be good could trigger action and an investigation by inspectors.

"If there is a pattern of lack of satisfaction from parents over a period of time, that really should be something we talk about and consider when deciding whether an inspection is needed," she said.

We are thinking about tailoring inspections much more Christine Gilbert, chief inspector of education

Ms Gilbert said the proposed reforms to the inspection system - which will include visits without warning - would come into force from September 2009.

She said inspections may focus in future on making sure standards in the three Rs improve.

It is "really shocking" that so many children leave primary school without being "fully fluent" in English and maths, she said.

Shadow Children's Secretary Michael Gove said: "Christine Gilbert is absolutely right that resources should be focused on those schools that need it most.

"It is something we argued for back in November."

Ms Gilbert said the plans could see primary schools being penalised if they fail to ensure that a certain proportion of their pupils master basic literacy and numeracy skills.

Although the best schools will be checked every six years, they will be subject to a "health check" every three years.

This will be a desk exercise conducted by experienced inspectors every three years, focusing on exam results and attendance levels, for example.