It followed violent protests at the Jebel Ali Industrial Area a week earlier. Although the exact cause of the riot remains unclear, wages and conditions are thought to be the root of the problem.

The incident comes almost a year after ruler of Dubai Sheikh Mohammed bin Rashid al-Maktoum ordered the federal government to improve working conditions.

At the time he said he would not accept any unjust treatment of workers. It followed a string of riots in 2006. Since then, the Labour Ministry has employed more inspectors and signed bilateral agreements with labourers' home governments. However, the latest incidents indicate that problems remain.

The region has relied on large numbers of poorly paid expatriate workers for decades. But despite saving on wages, the practice is hugely inefficient. 'We are throwing men at our projects and seeing little improvement in productivity,' says one sub-contractor working in Dubai.

The solution could be a smaller, more efficient and better-paid workforce. 'We did a study where we compared workers from Germany with workers from India and there is a massive difference in efficiency,' says a Dubai-based contractor.

'It is getting to the point where for certain trades we may start looking to Hanover instead of Kerala. I think there are lot of contractors waiting to see who will make the first move.'

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