The figure of 450 was reached after local authorities were surveyed on their foster carer recruitment targets for the next 12 months.

The number was calculated on the basis of the 21 councils - 66% of the total - which responded.

'Denied stability'

Robert Tapsfield, chief executive of the network, said: "Without these much-needed new foster carers, too many fostered children will continue to be denied stability in their home and school life, which is key to success later on."

Each fostered child should be able to live with a foster carer carefully chosen to match their specific needs in terms of location, lifestyle, language and culture.

The wider the pool of foster carers available, the more likely it is that a good match can be found.

More than 4,000 children live with 3,200 foster families in Scotland on any one day, with many more moving in and out of foster homes over the year.

Children's minister Adam Ingram said foster carers were often seen as a source of calm in the often turbulent lives of vulnerable youngsters.

"We want to encourage more people to consider fostering and I know how great the responsibility is that these carers take on," he said.

"As fostering fortnight begins I want to highlight the contribution that foster carers make and also how rewarding the role can be."

Foster Care Fortnight runs from May 12-25.