THE "brain drain" of international talent due to damaging immigration rules has cost the Scottish economy more than £250 million over the last three years, it has been claimed.

Universities Scotland said an extra 5400 international students would have lived in Scotland since the post-study work visa was abandoned in 2012 by the UK Government.

In a submission to MSPs, it calculated the fall in students from just two key countries, India and Nigeria, had cost the country £145.7million.

A further £108.6million had been lost as a result of universities failing to match the rate recruitment seen in the years before the scheme was scrapped.

The assessment will heap further pressure on the UK Government to devolve the powers necessary for Holyrood to establish a new scheme of its own.

In statement to the Scottish Parliament's devolution (further powers) committee, Universities Scotland said £254million was a conservative estimate of the economic losses.

The body said: "Scotland will have undoubtedly experienced a bigger negative economic impact as a result of this policy change in 2012.

"There would have been additional indirect economic benefits as a result of a larger number of highly skilled international graduates contributing to the Scottish labour market through increased productivity, increased tax contributions and disposable income once in employment."

It added: "We are unable to put an economic value on the social, cultural and educational cost to Scotland as a result of the closure in 2012 but the loss of this should not be underestimated either."

The post-study work visa was secured for Scotland by then-first minister Jack McConnell in 2005 as part of his "Fresh Talent" initiative to boost the population.

It was later rolled out across the UK but dropped in 2012.

Under the scheme, non-EU graduates were allowed to stay and work in Scotland for an additional two years.

It was credited with making Scottish courses more attractive to students from around the world.

The University Scotland paper revealed that between 2012 and last year, the number of students from Nigeria and India - previously seen as growing markets by the higher eduction sector - fell from 4515 to 3240.

It said any future scheme should allow those qualified to live and work in Scotland for at least two years after completing their studies.

The students spend £13,200 on fees and a further £6400 on living costs on average.

MSPs from across the political divide have called on the UK Government to reconsider devolving powers to create a replacement scheme.

The Smith Commission, whose recommendations formed the basis of the Scotland Act, said the prospect should be examined before the legislation was passed.

However, Scottish Secretary David Mundell appeared to rule out the move earlier this year.

Last week, UK immigration minister James Brokenshire again refused to commit to allowing Scotland to develop its own scheme.

In a letter to the Holyrood committee, the junior Home Office minister said "the case needs to be argued" for any changes and claimed that current UK-wide visa schemes for international students amounted to an "excellent" offer.