UNION leaders have called on Scottish ministers to bar companies which use zero-hours contracts from tendering for publicly funded work.

Firms which guarantee neither work nor pay should not benefit from lucrative public sector contracts, the Unite union has said in a letter to Scottish Finance Secretary John Swinney.

Last month, Scottish ministers suggested that they could ban companies which use the controversial terms from the tendering process.

The move followed reports that there are one million zero-hours jobs in the UK.

Councils, universities and high street chains across Scotland have all admitted using the contracts.

Unite pointed to recent revelations that zero-hour contracts are being used by sub-contractors on the £300 publicly-funded Borders Rail Link.

The Herald also revealed that the Church of Scotland's social care arm, Crossreach, is employing hundreds of staff on the terms.

Unite Scottish Secretary Pat Rafferty said: "Zero-hours contracts are a disgraceful employment practice that leaves workers in limbo - people don't know if they have a job or income from one day to the next.

"The Scottish Government condemns employment rights abuses like zero-hours contracts but also says it's for the UK Government to sort out. While it's true they can't end these practices, they do have the power to create minimum standards that all companies must adhere to when tendering for public contracts."

A Scottish Government spokesman said: "Employment policy is currently reserved to Westminster. However, we are actively considering whether issues around the use of zero-hour contracts can form a legitimate consideration for a public body as part of the public procurement process."