A second national strike across Scotland's colleges will take place in a dispute over pay.

Union members at 20 colleges across the country will strike on Tuesday September 6.

Members voted overwhelmingly for industrial action in a dispute which Unison claims results from college bosses awarding lecturing staff a £450 rise compared with the £230 increase they say has been offered to most support staff.

Read more: National college strike in Scotland is likely, unions warn

The strike aims to secure the support staff - including cleaners, administrators and technicians - parity with lecturers after talks between Unison, GMB, Unite and college bosses last week failed to find a resolution.

Lecturing staff at colleges across Scotland went on strike for a day in March earlier this year which centred on disputes over pay and led to the £450 settlement.

Chris Greenshields, chairman of Unison's further education committee, said: "Our demand is simple and fair. Pay college support staff the same flat rate rise of £450 that you gave to our teaching colleagues.

"We work for the same colleges, help deliver the same courses, support the same students and deserve the same cost of living increase."

Unison's Scottish organiser John Gallacher said: "Striking is a last resort but we will support our members in every way possible to achieve the same fair and reasonable pay settlement as already paid out to teaching colleagues.

Read more: National college strike in Scotland is likely, unions warn

"In a sector which sees top principals paid close to the salary of the Scottish First Minister, we should not be fighting over the difference between £230 and £450 for some 2,500 staff.

"Unison has written to every principal and every MSP in a last-ditch attempt to avoid this unnecessary and damaging dispute."

Staff at the following colleges plan to strike: Ayrshire, Borders, City of Glasgow, Dumfries and Galloway, Dundee and Angus, Edinburgh, Fife, Forth Valley, Glasgow Clyde, Glasgow Kelvin, Inverness, Lews Castle, Moray, New College Lanarkshire, North East, North Highland, Perth, South Lanarkshire, West, West Lothian.

Scottish Labour education spokesman Iain Gray accused the Scottish Government of breaking promises to college staff.

He said: "No-one wants to see industrial action but the SNP's record on colleges has been abysmal.

"SNP ministers promised college staff equal pay for equal work, then walked away from that promise. They have treated further education staff shamefully."

Colleges Scotland chief executive Shona Struthers said the strike action would bring "massive disruption to students and teaching staff", and called on members to abandon their plans.

She claimed the college sector could not cope with the £3.3 million which would be added to the college sector payroll by the union's demands, which she said "don't seem to recognise current public-sector finances".

She said: "Unison members have been offered the same percentage increase as lecturers which equates to 2.5% over two years. At the request of unions, the percentage has been offered as a cash increase.

"This means that support staff earning less than £22,000 have been offered a £400 increase to address low pay and for those earning more than £22,000, the increase amounts to £230."