Unite the Union say changes being proposed by the management at the Molson Coors brewery in Burton-on-Trent are denying workers' human rights.
It has balloted more than 400 staff at the brewery in a row over pay, shift patterns and terms and conditions.
“Our members, the vast majority of the workforce, are very angry at the hardline attitude of the management which could mean they are sacked and then re-employed on inferior contracts.
“The company has confirmed it also requires workers to be contactable during annual leave.
“Our legal team believes this is a denial of our members’ right to a private and family life which exists under the Human Rights Act.
In other words, workers will either be working, or available to work or be contacted, 100 per cent of the time, at any time of day or night.”
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Tahir Mahmood was detained by Police as he was attempting to climb into the roof space of an out-building at his family’s home.