Rural Scotland is seeing a new phenomenon of digital-era depopulation as people leave remote areas in search of faster internet speeds, the Rural Affairs Secretary has said.

Evidence is emerging of broadband-led rural depopulation amid concerns that nearly a fifth of homes in the Highlands and Islands will remain stuck on slower internet speeds, Richard Lochhead told MSPs today.

Finance Secretary John Swinney has pledged to ensure that 95% of premises in Scotland have access to superfast broadband by 2018, but some regions will fall short without additional funding, MSPs heard.

"The Scottish Government is very keen to step in with Scottish resources to try and ensure that we do all we can to connect our more remote and rural communities to the 21st century," Mr Lochhead told Holyrood's Rural Affairs Committee.

"There is now evidence of people leaving rural communities to live in urban areas, so there is rural depopulation due to a lack of connectivity.

"While you have traditional conversations about people leaving rural communities due to lack of access to higher education, affordable housing or employment, now there is an added factor where there is not good connectivity that can also lead to rural depopulation.

"Some research I have seen in the last year or so has started to show some evidence of that, and that should concern us all."

Highlands and Islands Enterprise expects to achieve at least 84% coverage by 2016 but other funds will be required to go beyond that, the agency's chief executive Alex Paterson told the committee last week.

The Scottish Government is lobbying for more resources to boost the region beyond "the low 80% range" by 2018, government deputy director for digital strategy and programmes Colin Cook told the committee today.

He said government broadband contractor BT is confident that 95% of the whole of Scotland will be connected by 2018, but confirmed that some regions will fall short without additional funding.

"Our contractors BT have expressed confidence that they will hit the (95% of Scotland) target, based on their experience in Cornwall and elsewhere," he said.

"I would like to repeat that from my side. I think we have got the team in place who have delivered the contract on time to date, in terms of negotiating it to the agreed timetable.

"Having said that, there will be regions of the country and local authority areas that will be beneath that target on current projections, and that is why we continue to lobby and argue for more money.

"The biggest issue remains across the Highlands and Islands which will probably be somewhere in the low 80% range by that time, and that is why we are lobbying for more resources to try and deal with that."

The Scottish Government is seeking a share of a £250 million UK Government broadband pot, will allocate additional Barnett consequentials to rural broadband, and seek support from local government and the European Union to boost speeds further, MSPs heard.