Talks between contractors and union leaders at a strike-hit oil refinery are being "actively encouraged" by owner Total. The French oil giant made the statement as workers gathered outside the Lindsey refinery, in North Lincolnshire, for a mass protest. Almost 650 contract staff working on a major construction project at the refinery were sacked last week by firms working for Total after a week of unofficial industrial action. Total said the action had left a construction project six months behind schedule and around £85.5 million over budget. A statement released by the company said further cost overruns would "jeopardise the future viability of this important inward investment into the UK". The firm urged discussions to focus on restarting the project and said it had been assured by contractors that workers would not face reduced pay or conditions. It said: "Total is actively encouraging talks to be opened between its contractors and the unions about how to facilitate the return to work of its contracting companies' former workforces. "These discussions between the unions and the contracting companies should focus on getting the project back up and running within the agreed timeframe and budget. "The contracting companies have assured Total they remain committed to the national agreement between themselves and the unions. "There is no question of a reduction in pay or dilution of existing terms and conditions." Total said it would be the end of the week before the number of contract staff wanting to return to work would be known. "However, the contractor companies have advised us that they believe they will have sufficient workforce necessary to meet their programming requirements," the company added. Speaking in reaction to the statement, Phil Whitehurst, of the GMB union, said he knew nothing about any proposed talks. He said: "I've spoken to the general secretary of the GMB, he knows nothing about any talks at all. Paul Kenny doesn't know anything at all about it."