Image copyright Getty Images Image caption The David Hume Institute said past policy had not successfully targeted Scots who settled elsewhere

A public policy think tank said a campaign was needed to target "wealthy, highly skilled" Scots living in places such as London to return.

The David Hume Institute believed the move was necessary to combat Scotland's shrinking working-age population.

Its director Jane-Frances Kelly said politicians needed to "get to grips" with the looming "demographic crisis".

The Scottish government insisted the country needed "tailored immigration solutions".

Pensioner numbers on rise

In its report, the institute - which is independent, non-partisan and conducts research aimed at aiding the formation of public policy - highlighted that by 2041 the working-age population of Scotland would rise by only 38,000.

In contrast, the number of people of pension age was expected to increase by 265,000 over the same period.

Its researchers made a number of recommendations, which included;

attracting more workers from the rest of the UK, including those from the Scottish diaspora

an immigration system that takes into account "different needs in different parts of the UK"

a system targeting both high and low skilled migrants

and politicians at both Scottish and UK levels "engaging constructively with meaningful proposals"

The institute said the working-age population crisis could be made worse by the UK's exit from the EU.

Ms Kelly said: "We are sounding a warning signal for Scotland's politicians and policymakers. We need to get to grips with the coming demographic crisis or Scotland's economy will be severely affected.

"There is a compelling case for the Scottish government to be able to adjust immigration to meet Scotland's unique challenge."

She added: "Our research shows how important increasing immigration will be to sustain the health of the Scottish economy.

"This means not just ensuring that existing migrants stay, but actively encouraging people to come to Scotland to live and work, including from the rest of the UK."

PA Scotland's ageing population 5,440,000Number of residents in 2019 31% Rise in over 75s since 1998

28% Rise in those aged 65-74

8%Decline in under 15s Source: National Records for Scotland

The report said that the Scottish diaspora was often wealthy, highly-skilled and "suited to many of the roles that Scotland needs to prosper".

However, it suggested that Scotland had not successfully cultivated this group of workers, "even though many of them are in London - less than 400 miles from the Scottish border".

The institute identified campaigns in Ireland, Australia and News Zealand where emigrants had been encouraged to return.

It highlighted the Irish marketing move by explaining: "In the 1990s, Ireland managed to reverse its pattern of net emigration by targeting Irish emigrants and their children. People returning home at Christmas and Easter vacations were welcomed with an invite to 'give Ireland a second chance'."

Europe and Migration minister Ben Macpherson welcomed the think tank's work on the issue and its recognition that Scotland needed to be able to "set its own migration policy".

He added: "People who've settled in Scotland from elsewhere in the EU significantly enrich our society and make a huge contribution to Scotland's economy and public services. They're our friends, neighbours and colleagues and we really want them to stay.

"In addition, as this report makes clear, we need to make it easier for talented hard working migrants to settle in Scotland and contribute to our economy and society."