The number of Glasgow City Council workers on zero hours contracts has increased by 18%, according to figures obtained by the SNP.

The Labour-led local authority and its arms-length organisations (ALEOs) employ 1,689 people with no guarantee of regular work, up from 1,436 in the previous year.

The majority of council employees on zero hours contracts work for the education department as supply teachers, classroom assistants and exam invigilators.

Two ALEOs - Glasgow Life and Cordia - employ people on zero hours contracts, the majority working in the hospitality and the "sport service" sectors.

When Labour Councillor Matt Kerr released the figures to Nationalist Councillor David Turner he confirmed in a letter that the contracts mean the council "has no contractual obligation to provide work".

Labour leader Ed Miliband and Scottish Labour leader Jim Murphy have made banning zero hours contracts a key plank of their election campaign.

Mr Murphy said Labour would "end the scandal of exploitative zero hour contracts", adding "It's no way to treat people who want to work hard and get on in life."

In a speech to Scottish Trade Union Congress delegates on April 20, Mr Miliband said he "will not tolerate (zero hours contracts) in the country I lead."

He added: "We will ban the exploitation of zero hours contracts and legislate to say that if you do regular hours you get a regular contract."

The SNP seized on the increase in casual workers at the Labour-led council, claiming Murphy and Miliband have "zero credibility on zero hours contracts".

Natalie McGarry, the SNP's General Election candidate in Glasgow East, said: "Jim Murphy and Ed Miliband proclaim their opposition to zero hour contracts with slogans on t-shirts, but actions speak louder than words.

"Almost 1700 workers at Labour's Glasgow City Council and its ALEOs are currently on zero hour contracts with no sign of the council helping these workers.

"It's time for real action by Labour rather than hypocrisy, slogans and soundbites."

The Evening Times understands many people employed on zero hours contracts by the council and ALEOs are entitled to holiday pay, sick pay and maternity pay, unlike private sector workers on zero hours contracts.

However Dave Moxham, Deputy General Secretary of the Scottish Trades Union Congress (STUC), who recently launched a campaign against zero hours contracts, said he still has "concerns" about the increase.

He added: "Whilst it seems clear that a proportion of these jobs are genuinely casual in nature, it is incumbent on the relevant council departments to review their staffing plans with the unions locally to assess whether there are better ways of managing service in a way which increases levels of employment security for those amongst this number who desire it."

A Labour Party source insisted its leadership would "unequivocally ban exploitative zero hours contracts".

The source added: "Glasgow Labour has led the way in challenging the use of exploitative zero hours contracts, by including them as a factor in its procurement process.

"The SNP should commit to banning exploitative zero hours contracts, instead they are merely kicking it into the long grass with a consultation.

"The SNP need to stop playing games with people's jobs and join Labour in committing to ban exploitative zero hours contracts."

The party source also pointed to a series of Tweets sent by Glasgow SNP councillor Mhairi Hunter in 2013, in which she said a zero hours contract "suited me" when she worked for the council as a waitress in the 1980s.

Speaking to the Evening Times yesterday, Councillor Hunter said: "I was talking about my experiences in the 1980s, which is another world. My thinking at that time was that kind of work suited me. It has since emerged that it is a bigger problem that perhaps I realised at the time.

"The increase in people employed on zero hours contracts by Glasgow City Council and its ALEOs is very concerning."