A council “bonus system” which see high-paid officials handed extra cash could be scrapped if the SNP seize power from Labour in Glasgow.

Executives can reward middle managers with a pay bump if they decide they have made a big contribution to the local authority’s objectives.

Many of those who benefit from the Additional Contribution Zone (ACZ) already earn between £40,000 and £70,000 a year.

Read more: Glasgow City Council 'shoring up' public relations operation as ex-BBC journalist bids for contract

Executive Directors have dished out more than £100,000 in ACZ payments in the last three years, according to figures seen by the Evening Times.

The SNP has said the system is “impossible to justify” as Glasgow City Council struggles to find saving of more than £130m in the next two years.

And union leaders at the local authority who are battling to protect workers’ terms and conditions have indicated they would not oppose the scrapping of the ACZ scheme.

The Herald:

However, the current Labour-led administration has indicated support for the system suggesting it could be a key policy battleground in the run up to the local elections.

In the three years from January 2013 more than 400 managers who are on grade 8 to grade 10 salaries were handed a share of around £100,000 in ACZ cash, according to internal figures.

The council’s pay and grading structure is made up of 15 grades and those at grade 9 to 14 are primarily in supervisory and management roles which attract salaries of between £40,000 and £130,000.

Read more: Problems mount for Frank McAveety at Glasgow City Council as top official is signed off sick

The majority of ACZ payments were given to employees with a salary range of £40,000 to £70,000.

High-paid officials in the education, environmental and social work department, as well as many who work for the chief executive, have benefitted from the scheme which has been described as a “bonus sytem” by one council insider.

The senior source, who asked not to be named, said: “This is a bonus system which favours senior officers and is in addition to the responsibility payments which are available to all staff at all levels.”

Read more: Councils behind Glasgow airport link say monorail proposals are 'not viable'

Executive Directors approve ACZ payments when an employee’s contribution “is recognised as being exceptionally high in meeting council’s objectives”, according to the policy.

It also states that employees can only be paid this “in exceptional circumstances for a defined period of time” but it is understood at least one senior member of staff has been in receipt of ACZ payments for four years.

Leader of the SNP group at Glasgow City Council, Susan Aitken, who is aiming to unseat Labour’s Frank McAveety at next year’s elections, said: “It is incumbent on those seeking to lead Glasgow that they should focus on preserving frontline services and ensuring that all staff are treated fairly.

“Given this, is it is impossible to justify the continuance of the ACZ system which allows senior officers to receive additional payments that are not available to front line staff.

“I believe strongly that a two tier system that privileges some staff over others is unacceptable, and that its removal will create a fairer and more transparent pay system for all council employees.”

Unison Glasgow branch secretary Brian Smith, whose union represents the majority of council workers, has backed the pledge.

He said: “Short-term, responsibility payments are usually transparent, justified and often associated with covering the jobs of workers on maternity leave for instance.

“Unison would however question two aspects of the figures. Firstly, managers earning nearly £50,000 or above are twice as likely to get short-term, responsibly payments than those below that wage.

“Secondly, more than half of these managers work in the chief executive’s department, the smallest in the council.

“Unison strongly urge that the council demonstrates with full transparency, that all of these payments are justified.”

A council spokesman said: “This scheme is used only in very limited circumstances to recognise exceptional performance and contribution, or to pay those who have had to make extraordinary changes to their working patterns.”