SCOTLAND is facing a demographic time bomb after new figures revealed the country's elderly population is predicted to rise by more than half a million during the next two decades.

The forecasts provide the starkest warning yet of the increased burden that will be placed on housing, care and health services in the coming decades, and call into question whether the policy of free personal care for the elderly is sustainable.

Analysts at the National Records of Scotland office believe the number of pensioners living in the country will swell by 551,200 by the year 2035.

The new figures released yesterday predict Scotland's total population will rise to 5.7 million by 2035, putting it on course to hit six million by 2050.

While most age groups are expected to remain stable, the number of pensioners is due to hit 1.4 million within 25 years, up from 879,500 today. An extra 21,500 over-65s have been added to the estimates, after the statistics were revised upwards from the last data released in 2008.

It means that within 23 years the percentage of Scots who are of pensionable age will rise from the current figure of 16% to almost 25%.

Campaigners yesterday called on the Scottish Government to rethink how it will provide for the hundreds of thousands of extra men and women who will rely on the state for care.

A spokesman for charity Age Scotland said: "By reshaping the current care agenda to invest more in care at home we can delay and avoid the need for more costly intervention in the future and deliver better services for older people which achieve significant savings for the public purse."

Graeme Brown, director of the housing charity Shelter Scotland, said: "A growing and ageing population will lead to increasing demands on vital services such as housing.

"The fact that population figures are growing will only heap further pressure on Scottish politicians who for decades have failed to address the chronic shortage of affordable homes. Investment in housing is investment in people and we urge the Scottish Government to build more socially rented homes for the families and individuals who need them."

The rise in the number of elderly people, which is fuelled by better healthcare and a bump in the birthrate during the baby boom years, is predicted to vary from area to area.

In East Renfrewshire, analysts expect the coming decades to swell pensioner numbers by 25%, while in West Lothian and the Shetland Isles their ranks will nearly double.

About 37,000 pensioners will be living in Glasgow, where the population overall will rise by 74,000, while 47,000 people living in Edinburgh will be over 65 years old.

Some areas will be hit by a double whammy of a drop in the number of young people coupled with a rapidly aging population who stay behind.

In the Western Isles, the current population of 26,196 is expected to decline 3,000 by 2035, while the number of pensioners will increase from 5,700 to 8,900. The population overall is predicted to be 23,220.

Archie Campbell, chairman of sustainable development for Western Isles Council, said he was "seriously concerned" about the challenges the coming decades would bring.

He added: "The increase in those of pensionable age would put enormous pressure on social care and other budgets. There is therefore a major challenge for the council and other agencies to at least stem the population decline and hopefully reverse it."

A spokesman for the Scottish Government said: "We recognise an ageing population presents challenges to our health and social care system, which is why we are ensuring older people receive the care, compassion, support and dignity they need and deserve.

"Lord Sutherland made it clear in his independent review of Free Personal and Nursing Care in 2008 that the policy was benefiting over 40,000 vulnerable people, and that it was sustainable at that time for the next five years, but that we need to adapt the policy to address demographic changes in the medium and longer term."