The report assessed spending on foster care

A report, by the Fostering Network and the British Association for Adoption and Fostering (BAAF), made detailed calculations to estimate the shortfall.

The Cost of Foster Care outlined the spending required to give children in care the same opportunities as others.

The Scottish National Party said the shortfall was "shocking" and urged the Scottish Executive to act immediately.

The report, which found a �748m shortfall across the UK, were based on assumptions about how to provide high standards of care.

Assumptions included giving all foster carers the Fostering Network's minimum allowance and paying a fee to all foster carers, who made themselves available 52 weeks of the year.

Robert Tapsfield, chief executive of the Fostering Network, said it was the first time such a "substantial and robust" calculation had been made.

'Shocking shortfall'

"This is a call to the governments of the UK to invest a further �748m in foster care services each year," he said.

"We should ensure that the outcomes for children in foster care are the same as those we want for our own children."

SNP children's spokeswoman Fional Hyslop said: "This is a shocking shortfall of resources for children in need in Scotland.

"Children's care services have been a Cinderella area of government support for too long.

"The executive has always known about shortages of children's social workers, it has known about these children's poor educational attainment and have known that there is a shortage of foster carers.

Children's care services have been a Cinderella area of government support for too long Fiona Hyslop Scottish National Party

"The executive must reassess levels of funding for children in need immediately."

The report said that about �50m was currently invested in fostering in Scotland, which included foster carers' fees, allowances and training.

A Scottish Executive spokeswoman said they did not recognise the figures quoted in the report.

"The executive provides �1.8bn a year for council-run social services, including foster care," she said.

"In addition we have made an extra �12m available over the next two years specifically for fostering, an announcement welcomed by the Fostering Network."