Standards of education in England are improving, but the nation is falling behind its international competitors due to “mediocre teaching” and “weak leadership” in too many schools, Ofsted has claimed.

In its latest annual report, published today, the watchdog revealed that almost eight out of 10 schools were judged to be good or outstanding in their most recent inspection - the highest proportion since Ofsted was founded two decades ago.

The FE sector, subjected to stinging criticism in last year’s report, has also “raised its game”, chief inspector Sir Michael Wilshaw acknowledged, with a 7 per cent increase in the proportion of colleges judged to be good or outstanding.

But England is struggling to compete with other nations due to regional variation in the quality of education and the “significant underachievement” of white children from poor families, the report says. Overall, almost a quarter of a million pupils attend schools rated inadequate by Ofsted, it adds.

“Serious challenges remain, and all the while, many of our international competitors are improving at a faster rate than we are,” Sir Michael said.

According to the 2012 edition of the Programme for International Student Attainment (Pisa) published last week, the UK’s performance had flatlined, with the country being ranked 26th in the world for maths, 23rd in reading and 21st for science.

The chief inspector also called on the government to consider a return to “more formalised testing” of seven-year-olds at the end of Key Stage 1 to ensure that every child is making adequate academic progress.

Sir Michael also announced that a series of no-notice inspections will be launched in January to tackle schools suffering from poor behaviour.