David Miliband said he was appalled by the UK's ranking in comparisons produced by the Organisation for Economic Co-operation and Development.
"It must be one of the most stunning statistics that we are 20th out of 24 OECD countries for staying-on rates at 17," he said.
Even worse was the position of 22nd for the numbers still in education or training by the age of 18.
In an interview with the Independent newspaper, Mr Miliband said: "This is a national shame, and it is a national disgrace that we still talk of people staying on after 16 rather than dropping out."
Changes ahead
Next month the government will be publishing the conclusions it has drawn from the responses to its consultation on reforming 14 to 19 education in England.
The priority will be to make schooling for children aged 14 to 16 more flexible, in an effort to re-engage those who are turned off by academic study.
Pupils will be able to pursue a vocational or academic path, through schools, colleges and workplace training, following courses that best suit their abilities and aptitudes.
Under the original proposals, the core of the curriculum that all pupils must study would be mathematics, English, science and information and communication technology, alongside citizenship, religious education, careers education, sex education, physical education and work-related learning.
This would drop the present requirement to study design and technology and - most controversially - a modern foreign language.
But Mr Miliband said the idea of a new, three-tier qualification for 19 year olds, called the "matriculation diploma", had been postponed.