College lecturers are being balloted on strike action for a second time as part of a long-running dispute over pay.

The EIS trade union has begun sending out statutory ballot papers to members of its Further Education Lecturers' Association (EIS-FELA), with leaders demanding college bosses honour a deal that was agreed last year.

College staff walked out on strike for a day in March 2016, and had more than 30 days of action planned.

A revised offer from Colleges Scotland was accepted with staff promised wage rises as well as work between colleges and the union to develop a more ''harmonised'' pay deal across the workforce.

But EIS general secretary Larry Flanagan claimed the union was still waiting for that to be delivered.

He hit out: "After more than a year of waiting for colleges to deliver this binding agreement that was supposed to deliver pay harmonisation across the country, the patience of Scotland's further education lecturers is now exhausted.

"The degree of obfuscation from college managers over the non-delivery of the agreement they freely signed up to over a year ago has been simply incredible.

"Firm promises were made to lecturers on pay harmonisation across the sector, following many years of differing pay for lecturers doing the same job in colleges across the country.

"It is now time for college managers to stop their negative spin about the deal and to deliver the agreement that was struck last year."

An indicative ballot of college staff has already shown "overwhelming" support for more action, according to the EIS, with the statutory ballot now due to run until April 10.

EIS-FELA president John Kelly added: "While no lecturer relishes the prospect of taking strike action, the inaction of management on the delivery of this year-old agreement has forced us to pursue this dispute.

"We must increase the pressure on Scotland's college principals to compel them to honour the deal and deliver their promises on fair pay for all lecturers across Scotland."

Colleges Scotland has stressed it wants to avoid "unnecessary and disruptive" industrial action by lecturers.

A spokeswoman said that staff had already received a pay rise and "good progress" was being made in a number of other areas covered by the deal.

The Colleges Scotland Employers' Association said students and the college sector can only be damaged by the EIS's "unreasonable demands".

A spokeswoman said: "Employers have already agreed to deliver an average 9% pay increase for lecturers over the next two years but the EIS also wants an increase to 66 days holiday and a reduction to just 21 hours class contact for teaching staff, and remains unwilling to compromise on overall reforms to pay and conditions of service which were jointly agreed last March.

"The EIS demands can only mean less teaching time for students at a higher cost to the taxpayer.

"As well as the 9% average pay rise over the next two years - following a pay increase for lecturers this year that was above public-sector pay policy recommendations - we are offering 56 days annual leave and up to 26 hours class contact time.

"We firmly believe this is a good package that people in other sectors would warmly welcome yet the EIS seems determined go down the road of disruptive strike action instead."

She added that parties have agreed to meet again on Thursday to continue talks.

The Colleges Scotland Employers' Association said students and the college sector can only be damaged by the EIS's "unreasonable demands".

A spokeswoman said: "Employers have already agreed to deliver an average 9% pay increase for lecturers over the next two years but the EIS also wants an increase to 66 days holiday and a reduction to just 21 hours class contact for teaching staff, and remains unwilling to compromise on overall reforms to pay and conditions of service which were jointly agreed last March.

"The EIS demands can only mean less teaching time for students at a higher cost to the taxpayer.

"As well as the 9% average pay rise over the next two years - following a pay increase for lecturers this year that was above public-sector pay policy recommendations - we are offering 56 days annual leave and up to 26 hours class contact time.

"We firmly believe this is a good package that people in other sectors would warmly welcome yet the EIS seems determined go down the road of disruptive strike action instead."

She added that parties have agreed to meet again on Thursday to continue talks.