Audi and BMW employees have joined Porsche workers in striking.

Strike action in Germany's motor industry has spread wider after last weeks walkout at Porsche, with staff at Audi and BMW now walking out.

Both sides are currently thrashing out a deal over working hours which they hope to be finalised before February, according to Reuters, but if the talks fail to progress, more workers could join the 160,000 that have already staged protests.

The IG Metall union in Germany is looking for a 6 percent in pay for nearly 4 million workers in the industry, and says that such a raise is possible thanks to record low unemployment and the fastest economic growth in six years. Industry workers are also looking for a decrease in working hours – their first such campaign in more than 30 years.

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IG Metall's proposal is to give workers the right to reduce their hours from 35 hours a week to 28 in order for workers to care for children, or sick relatives and then return to full-time employment after two years. Another demand is for employers to make up for the pay lost by those who choose to cut their hours. That idea has been rejected too.

Employers have already offered a two percent raise along with one-off payment of just under £200 as a compromise, having branded the demands as 'excessive', but workers aren't budging. They've also said if employees want a shorter working week, hours would have to actually be increased initially to maintain output.

In Baden-Württemberg, in the south-west of the country, a breakthrough was made on Thursday, with an agreement being made to appoint experts to examine working hours, and any such deal struck in the region is likely to be carried over across the rest of the country.

Talks are set to resume next week, but it is unclear as to whether a resolution is near. Based on previous labour deals by IG Metall, analysts at Barclays are predicting a wage increase of around 3.2 percent, but that it will likely come after an as-yet unscheduled fifth round of talks.