Thousands of tanker drivers are to be balloted for industrial action in a row over pay, pensions and working conditions.
The union Unite warned employers that voting was likely to start next month unless the "constant attack" on drivers' terms and conditions stopped.
The union claimed that contractors responsible for the delivery of oil and petrol supplies to petrol stations and supermarkets across the UK had "squeezed" the pay and conditions of around 3,000 drivers.
Unite said it was calling for national standards to stop a "race to the bottom" on pay and conditions and claimed employers had refused to hold talks over the row.
Unite's new leader Len McCluskey said: "Tanker drivers play a crucial role in the economy."