Engineering construction workers from Wales, Nottingham and North Lincolnshire are expected to swell the ranks of workers fighting to get their jobs back at the Vivergo biofuel site near Hull.
Around 400 workers were locked out several weeks ago when sub-contractor Redhall Engineering Solutions became bogged down in a dispute with plant owner Vivergo.
Union bosses have blasted the actions of Redhall Engineering Solutions Ltd, Vivergo and project manager Aker Solutions.
None of the companies are accepting the workforce is their responsibility, with Redhall insisting the workers have been transferred to Vivergo under employment regulations.
Now workers are demanding their jobs back and will be joined today by workers from North Lincolnshire refineries Lindsay and ConocoPhillips, Pembroke power station in Wales and Ratcliffe-on-Soar power station in Nottinghamshire.
Keith Gibson, of the general union GMB, said: “We will have upwards of 1,000 people coming down.
“They are joining us in solidarity because this could have wider implications for workers everywhere.
“The workers have been locked out and this could happen to others anywhere in the country.”
Redhall claims it is owed £14m after its contract was terminated by Vivergo which is a joint venture between BP, British Sugar and DuPont.
Redhall said it has completed 78% of the original contract plus variations and there are currently approximately £14m of costs on the contract unpaid.
Vivergo issued a statement saying they had cancelled the mechanical and piping works contract because the works “should have been completed by February 2011″.