SCOTLAND'S population reached its highest ever level last year after record numbers of immigrants helped fuel the biggest increase in new residents for more than 50 years.

A report from the General Register Office for Scotland estimates there were 5,254,800 people living north of the Border in 2011, a rise of 32,700 from the previous year.

More than 42,300 immigrants, including asylum seekers and 10,000 Scots returning home, came from overseas to settle in Scotland – half of them from Europe with the rest spread out from across the globe. Although 16,900 people left the country during the same period, the net increase of 25,400 incomers is the biggest since estimates began in 1991/92.

Coupled with the second-largest natural increase in modern times, with births outstripping deaths by 4800, the newcomers and returning Scots have pushed the population to a record high.

The Scottish Government welcomed the population boom, saying new arrivals are needed to expand Scotland's economy.

The record increase also outstrips the number recommended by the council of economic advisers to meet growth targets.

However, support agencies have warned the rising population will heap pressure on already stretched support services such as housing and healthcare.

Graeme Brown, director of Shelter Scotland, said: "A growing and ageing population will inevitably lead to increasing demands on vital services such as housing. In Scotland there is already a shortage of affordable and socially-rented housing, with 156,000 households waiting for a home. The fact the population is now at a record high will only heap further pressure on Scottish politicians who for decades have failed to address the chronic shortage of affordable homes."

A spokeswoman for the elderly care charity Age Scotland said those making their homes in Scotland would have to be prepared to help pay for the needs of an increasingly ageing population.

She said: "While people in Scotland are living longer, this has coincided with higher levels of dementia, restricted mobility, sensory impairments and the associated costs of providing support for people with these conditions. Scotland's low birth rate means projections about how we deliver this care in the future have highlighted concerns about the disparity between the number of people receiving care and those available to provide or pay for that care."

Net immigration from the rest of the UK was also greater than the number leaving Scotland to live in England, Wales or Northern Ireland, with more than 43,000 people arriving compared to the 40,800 heading in the opposite direction.

The record for Scotland's population was set in 1974 when it reached 5,240,800, but the number decreased in subsequent years. It is now estimated to have increased by almost 200,000 during the past 10 years, rising from 5.06 million in 2001 to 5.25 million last year.

George MacKenzie, registrar general for Scotland, said: "Scotland's population has reached its highest ever. The increase in the year ending in June 2011 was the ninth annual rise in a row, and the highest for more than 50 years. This was partly because there were more births than deaths, but migration accounted for most of the rise. Fewer people came to Scotland from the rest of the UK than in recent years. But the net gain of around 25,400 people from overseas was the highest since current estimates began in 1991/92."

A Scottish Government spokeswoman said: "We are working hard to promote Scotland as a positive place to live, work, study and remain. Today's statistics show our hard work to grow Scotland's population to support economic growth, is paying off."