Nearly 1,000 jobs are thought to be in jeopardy amid reports that an oil refinery that went bust is likely to be closed and turned into a storage terminal.
The Coryton plant in Essex, which is the biggest provider of petrol and diesel in the south east of England, was plunged into administration by its Swiss owner Petroplus in February.
A deal with a consortium of financiers to keep the plant running for three months expired on Wednesday but administrators are still scrambling to find a buyer.
Vitol, the world's largest independent oil trader, is understood to have dropped out of the auction last week and although another bidder is still interested, the plant could now be shut and turned into a storage terminal.
It has been reported that a tanker reached the plant last week with enough crude oil to keep the site working for 11 days but the plant is unlikely to carry on operating beyond the end of this month.
Administrators had previously said that the plant would close by the middle of May unless a deal was reached.
As well as seeking a potential buyer, administrators at PwC have been trying to engineer a one billion US dollar (£632.6 million) deal with its banks and creditors to keep the plant running in the medium-term.
After taking over the running of the plant, they discovered that the refinery has debts of £2.3 billion US dollars (£1.5 billion).
East of England MEP Richard Howitt believes about 80% of the jobs at the site would go if it was converted into a terminal, which would be "a disastrous outcome for all involved".
He added: "Converting Coryton into a terminal would be a low-grade solution for a high-grade product."
He is meeting representatives of a remaining bidder this week and said there was still hope of a deal.