College support staff are to go on strike for the second time in a month in a dispute over pay.

Unison Scotland and the GMB have announced a day of industrial action on September 27, with two more consecutive strike days planned for October.

Support workers at 20 further education institutions walked out earlier this month, causing disruption to students with cancelled classes and the closure of campuses at West College Scotland and New College Lanarkshire.

The unions argue that 2,500 members - including catering and cleaning staff, classroom assistants and librarians - are being treated as ''second class citizens'' after being offered a flat rate pay rise of £230 compared to £450 for teaching staff.

Lecturers went on strike for a day in March earlier this year which led to the £450 settlement.

Chris Greenshields, chair of Unison Scotland's further education committee, said: "Striking is a last resort and we're disappointed the employers have not listened to our calls for fair and equal treatment.

"In 2015, every single support worker and every single lecturer received £400 as a pay rise. The employers agreed an 'equality clause'. What is different in 2016? Why should one portion of staff get £450, another £400 and yet another £230?

"It is a divisive negotiating strategy and Unison will only accept fairness and justice for all."

Cal Waterson, full-time official of the GMB, said: "Our ballot result was the most emphatic I have ever seen. I have never known such anger among our members who see the complete unfairness in the way they are being treated in these pay negotiations and the hypocrisy of the employers.

"Many of our members are being offered less than 1%, while managers receive four-figure pay rises and five-figure annual contributions to their pension pots."