The scheme will be tested over two years across companies seeking labour reforms that can “generate a rise in productivity which compensates salary costs” whereby wages are maintained, the labour ministry said.

Firms interested in joining the pilot must commit to cutting weekly hours by at least ten percent over two years for at least a quarter of their staff.

In return they will receive state assistance designed to compensate for the impact on production as well as additional administrative costs which may arise from putting the scheme into operation, the ministry said.

After assessing the effect on productivity the ministry said the government would then determine whether to “roll it out to the rest of the economy.”

Recent years have seen several large Spanish companies — including telecoms giant Telefonica and fashion group Desigual test or in some cases adopt the four-day week. However, few of those cases have been in industry and have also mainly been accompanied by a corresponding drop in wages.

The issue has proven a sensitive one with unions largely in favour but bosses opposing a measure they see as difficult to apply across numerous sectors of the economy.