PwC said there was also at least one bidder who intended to keep refining, preserving the 850 jobs at the site, or possibly even creating more jobs by increasing operations.

A three-month "tolling agreement" keeping Coryton operational will run out by May 16, when the site could face closure.

Steven Pearson, joint administrator at PwC, said: "If we haven't extended the tolling agreement, if we haven't refinanced it and we haven't got a buyer, there are no other options. If we don't get a deal done, we have to close it.

"If it's sold as a terminal there will be very substantial job losses."

At peak production Coryton refinery provided fuel to 20pc of London and the South East, prompting fears of forecourt shortages if it were to close. However, there is overcapacity in the UK refining sector and a temporary halt to Coryton's deliveries in January caused little disruption as other refineries increased their output.

Mr Pearson declined to comment on the identities of the bidders but it is thought some may be consortia of several companies.

Prior to the April 2 deadline for bids, those expressing interest included The Goldsmith Group, run by German investor Clemens J Vedder, and Gary Klesch of Swiss investment vehicle Klesch Group. The former Russian energy minister Igor Yusufov was also reported to be interested.

Mr Klesch told the Telegraph at the time that he would intend to keep it running as a refinery.

Swiss-based Petroplus filed for insolvency in January, hit by high debt and low refining margins.

Petroplus Refining & Marketing Limited (PRML), the UK business that owns Coryton, owes creditors more than $2.3bn (£1.47bn). Administrators have indicated they favour a debt-for-equity refinancing deal with the creditors to allow PRML to continue refining, in the belief it offers them all parties a better outcome than a sale.

About $1.75bn of PRML's debt relates to guarantees on bonds and notes issued by other European Petroplus companies, despite their being in separate administration proceedings.

PwC met the bondholders in March and told them that a debt-for-equity swap could offer good long-term value as the company was "capable of generating very significant earnings".

However, PRML would also need about $1bn of new financing to keep running.

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