Workers on Scottish Government projects paying to access their own wages through agencies are choosing to do so, the First Minister has claimed.

Concerns have been raised over the practice after it emerged some workers on the new Aberdeen bypass scheme (AWPR) are employed through agencies who are charging them to be paid.

A trade union representing the workers has disputed the First Minister's account.

Nicola Sturgeon was quizzed on the practice at First Minister's Questions on Thursday by Scottish Labour leader Richard Leonard for the second week in a row.

Leonard asked the First Minister what action she had taken over the last week on the issue.

She said Transport Scotland completed an urgent investigation into the practice which found an agency was doing so on behalf of a subcontractor for the project.

"It is at the discretion of individual employees if they choose to work through an agency," Sturgeon said.

"At the AWPR, there is no requirement to do so because the subcontractor offers to directly employ all employees working on the project.

"That means any worker who wishes to be paid directly by the subcontractor can be, which avoids any of these practices which I would condemn by agencies being applied."

Leonard said there are examples of other cases on Scottish Government-funded projects.

He asked: "First Minister, isn't it the case that you have no idea how widespread this practice is on the public projects that you fund?"

Speaking after hearing Sturgeon's comments Stevie Dillon, Unite regional officer said: "Unite Scotland has no knowledge whatsoever of workers on major infrastructure projects in Scotland being offered a choice of direct employment with major contractors.

"One system dominates this entire section of the industry. A recruitment agency approaches the worker with a job offer.

"If the offer is accepted the worker is then directed to sign up with a specific company-which will be one of the rip-off 'umbrella' contractors."