Too many pupils are being denied the chance to take part in competitive sport by state schools who treat it as an "optional extra", Ofsted has warned.
In a new report, the chief inspector said children's education was poorer if they were deprived of the chance to compete.
Sir Michael Wilshaw suggested that many state schools were failing to offer good quality competitive sport when it should be seen as key to helping boost children's results in the classroom and exam hall.
Ofsted's new report, commissioned after the 2012 London Olympics, examined why so many winning athletes come from private schools rather than the state sector, and the links between the quality of competitive school sport and sporting success later in life.
It found "unacceptable discrepancies" between the proportion of pupils attending state schools and how well they were represented in elite sport.
Fewer than one in 10 pupils across England attend fee-paying schools, but they make up the majority of the players in the English Rugby Union Premiership, the watchdog said.
Privately educated students also accounted for more than a third of top-flight cricket players, it added.
The study, based on visits to 10 independent schools, 35 state schools, plus surveys of headteachers and 11 to 18-year-olds, concluded that competitive sport remained optional in the vast majority of state schools.
In many state schools, the quality of competitive sport was no better than average, while in a significant number it was weak, inspectors warned.
Half of the 1,000 young people questioned said they regularly played sport in school against their classmates or other schools, while 40% said they regularly played sport outside of school.
The report found that the best schools' competitive sport was flourishing because it was valued and seen as a key part of the culture and ethos.
Coaches were hired to work alongside teachers and coach school teams, while teachers gave up their time to help organise activities and run teams.
But it added: "In too many of the other maintained schools and academies we visited, students had few opportunities to excel in competitive sport because it was not seen as a priority.
"It was undervalued by school leaders, who were not investing in it."
These schools were less likely to be rated good or outstanding, Ofsted said, and typically had lower levels of academic achievement than those state schools that offered high-quality competitive sport.
The report did note that limited facilities were a factor in preventing some state schools from helping their pupils to excel on the sports field.
Eight of the state school and academies visited had a swimming pool, it found, 16 did not have a multi-use games area with an all-weather surface and one academy did not have playing fields.
Inspectors suggested that helping pupils to train and play sport outside of school hours was easier with good facilities and supporting competitive sport was much more difficult if a school lacked these facilities.
In a foreword to the report, Sir Michael said that private schools performed better at sport not because they had better resources, but because of their attitudes to the subject.
"As things stand, many state schools treat competitive sport as an optional extra or fail to offer it in any meaningful way," he wrote.
"They get on the bus but fail to turn up on the pitch.
"This matters not because I expect every school to produce a Mo Farah, but because children's education is the poorer if they are deprived of the chance to compete."
He added: "The real value of competitive sport is the positive effect it has on education.
"Schools that win on the field win in the exam hall."
Sir Michael, who is due to present the report at the Festival of Education at Wellington College tomorrow said: " Heads who treat competitive sport with suspicion or as an optional extra are not only denying youngsters the clear dividends that come with encouraging them to compete, they are also cementing the social inequality that holds our nation back."
He added: " More state schools are now encouraging sporting excellence.
"They use competitive schools sport to energise the entire school culture.
"They demonstrate that high school fees and large playing fields are not a pre-requisite to success.
"If all schools follow the example of the best identified in this report, there is no reason why more pupils from state-funded schools can't be batting for England at the Ashes or scoring a winning try in the next Six Nations."
John Steele, chief executive of the Youth Sport Trust, said: "The findings from this report highlight a worrying inconsistency in the provision of competitive sport being offered in state schools.
"It is encouraging however, to see that where state schools take competitive sport seriously there is a clear correlation to academic attainment.
"Not only does PE and competitive sport build confidence and self esteem, it plays an integral role in boosting academic achievement across all areas of education.
"This report should be a wake-up call for those schools that do not fully value its place in school life."
A Department for Education spokesman said: "We absolutely agree that sport should be a priority for schools.
"That's why we are giving primary schools over £150 million a year specifically for sport and PE. A typical school will receive £9,250, enough to pay for a specialist PE teacher for a day a week to work alongside existing staff.
"Too few children have been taking part in competitive sport in recent years. That is why we are strengthening competitive sport in the new curriculum at all key stages so that all pupils learn to compete against their peers.
"The new curriculum also encourages pupils to build strong links to community sport outside of school hours."
Geoff Barton, head of the state comprehensive King Edward VI School in Bury St Edmunds in Suffolk, told the BBC Radio 4 Today programme: "I kind of wish Michael Wilshaw would stop pontificating so much, because people like me in schools like this see competition all the time.
"We simply don't recognise the language he uses, and for me the most infuriating part of it is that there are parents round here who may be making a decision about whether to send their child to a state school like ours or an independent school, who will hear his stereotyping of the state sector and decide they are then going to move into the independent sector.
"We've got somebody who presided very successfully over state comprehensive schools who is sending the very parents who we should be winning into our schools away. I think that is really shameful."
But Sir Michael told Today: "The facts speak for themselves, and people who read our report will see what those facts are, in the percentages of youngsters who do well from the independent and state sectors. We are saying that balance needs to be addressed.
"What we've got to start talking about in the state system is excellence, we've got to start talking about competition and elitism. We've got to make sure that all those things that they do well in the independent sector are replicated in the state system."