Hundreds of 16-year-olds are being "pushed out" of Scotland's overstretched care system every year, the nation's children's commissioner warns.

Kathleen Marshall, in a biting report published today, says more than half of all youngsters who left care were 16, many of them vulnerable to homelessness, drugs, drink and unemployment.

The number of looked-after children hit its highest level since the recession of 1982.

Ms Marshall said: "In many cases children and young people in care are seen as a troublesome burden rather than a vulnerable person to be nurtured. At 16 - the time they need help to cope - many are all but completely abandoned with little, if any aftercare."

Senior social work sources said 16-year-olds were being squeezed out to make way for an army of needy children - many the offspring of a wave of drug addicts.

Successive Scottish administrations have striven to keep young people in care longer. Ms Marshall, however, found some 16-year-olds were still leaving care with nowhere to go.

More than one in 10 reported episodes of homelessness. Some were sent to bed-and-breakfasts - at least one youngster had to share accommodation with a convicted murderer.

The commissioner calls on the Scottish Government to ban B&Bs for care-leavers, one of 23 recommendations she makes in her report, called Sweet 16.

Tam Baillie, of the charity Barnardo's Scotland, which runs services for care leavers, said: "Nowadays, most young people stay at home well into their 20s, yet most looked-after young people leave care aged 16 or 17. We need to ask ourselves why our most vulnerable young people are expected to be fully independent at such a young age."

Bernadette Docherty, president of the Association of Directors of Social Work, said: "Local authorities do not set deadlines for moving on and most actively seek to support young people until they are ready to live independently. However, the most difficult and needy often leave the system too early."

A spokesman for the Scottish Government said more needed to be done "to help them make the transition to independent living". He added: "That's why we're working with councils to ensure that care-leavers are housed appropriately as part of the We Can and Must Do Better' strategy and have made clear that young people should remain in care until 18 if it is in their best interest."