Statistics obtained by Express.co.uk show 429 claims of sex crimes at the capital’s schools and nurseries were reported to police in 2014/15.
The figure soared by a staggering 68 per cent from 2013/14 to last year, while the number of alleged rapes rose from 25 to 49.
And, where the ages of offenders are reported, incidents in which under 18s are believed to be responsible have increased by 65 per cent, as opposed to a rise of 43 per cent in adult offenders.
These figures should be a wake up call to all schools
A third of the alleged rape victims were girls aged under 16, with 16 coming forward. A dozen boys aged under 13 also reported being victims of the crime.
A spokesman for the NSPCC called the information “disturbing”.
He said: “Schools should be safe places where pupils can fulfil their potential. So it’s disturbing that so many children have been subjected to horrific sexual crimes including rape.
“These figures should be a wake up call to all schools to ensure all pupils feel able to speak out and seek help whenever they need it.”
The shocking figures should be a ‘wake up call’ for schools, the NSPCC said
The charity’s spokesman said more must be done to identify and help children who are at risk of becoming offenders.
He said: “Children accused of sexual offences have often been victims of abuse, harm and trauma themselves.
“If we are to tackle this growing problem and protect young victims, more needs to be done to identify and treat children who might commit offences.
“All children need to be educated about what sexual abuse is and how to get help immediately if they or someone they know has suffered an attack at school.”
The Metropolitan Police said rape victims more comfortable coming forward
The number of boys under 13 who were allegedly sexually assaulted on the premises of schools and nurseries rose by 140 per cent between 2013/14 and 2014/15, according to the figures.
And the number of females who reported the same offense spiked from 76 to 123 between the same years – a rise of 62 per cent.
But a Metropolitan Police spokeswoman said the rising number of rape allegations “reflects a greater confidence” that victims will be listened to.
Express.co.uk obtained the police data under Freedom of Information laws
She added: “All reports of rape are thoroughly investigated and each victim has their case dealt with by a specially trained officer.
“The increase in reporting in respect of offenses mirrors the national increase in reporting, which has been evident since 2012.
“The MPS has increased its investigative capability to address this rise and to provide victims the outcomes they want.”