Some 900 jobs are at risk at the plant, formerly owned by the now-bankrupt Swiss-based company Petroplus. Administrator PricewaterhouseCoopers has indicated it is unlikely to find a buyer to keep Coryton running as a refinery.

Union officials said they would aim to disrupt supplies of fuel from nearby terminals for a few hours every day and that the action would continue as long as needed.

Drivers with logistics firm DHL, who take fuel to supermarkets, are refusing to drive past the demonstration on health and safety grounds.

"This action needs to be stepped up. The government needs to recognise they still have an important part to play in saving Coryton," said Russ Ball, a regional representative for the Unite union.

Petroplus fell victim to a rapid debt-fueled expansion and a collapse in profitability of European refining. But its four other refineries in Germany, Switzerland, France and Belgium have found buyers or suppliers and are not set to close.