Tony Blair is said to have ordered an inquiry into why so many children in care leave school without a single qualification.

According to a report in The Guardian, Downing Street's social exclusion unit is sending out questionnaires to local authorities in an effort to find out why children in residential and foster homes do so badly at school.

Last year, seven out of ten teenagers left care with no qualifications and just 4 per cent had five or more GCSEs at grade C or above, compared with a national average of nearly 50 per cent.

The Government is currently aiming to cut the numbers of children failing at school to 25 per cent by 2003 and to increase the proportion leaving with five A-C GCSEs to 15 per cent by 2004.

Official figures show that up to one in three rough sleepers and one in four prison inmates were in care as children. Looked after youngsters are also two and a half times more likely to become teenage parents and at greater risk of unemployment.