The warning comes from the company’s chairman, Jacques Gounon, who faces a crucial board meeting tomorrow and a showdown for control of the company at its annual meeting on Friday.

Gounon told The Sunday Times that he had given himself until October to see if there was a realistic chance of reaching agreement with creditors, who are owed about £6.4 billion.

If he failed, he said, he would ask the board and the company’s auditor, KPMG, whether Eurotunnel could be considered a going concern for the purposes of its 2005 accounts.

“If at the end of October there is no solution, I will have to approach the board for a decision as to whether we’re a going concern,” he said.

This would constitute a default by the company on the terms of its loans and allow creditors to step in and take control, leaving shareholders with nothing.

“Even if they take over, they will still have the same challenge that we have — that is, designing a scheme that will solve the company’s problems,” said Gounon.

There were signs this weekend that creditors were taking tentative steps to prepare for a collapse. Banking sources said there could be talks in the next few weeks between leading creditors and British and French government officials to establish a framework for an orderly transition.

Eurotunnel, which was set up in 1986, has a concession to run the Channel tunnel until 2086. Last year it carried 1.3m trucks and 2.1m cars between England and France.

The company, which is struggling to survive under a mountain of debt, was rocked on Friday by the resignation of chief executive Jean-Louis Raymond. The board will meet tomorrow to appoint an interim chief executive.

Another crisis looms on Friday, when Gounon stands for election as a director at the company’s annual meeting. He may face opposition from Nicolas Miguet, the share tipster and former French presidential candidate, who last year helped to organise a shareholder revolt that overthrew the previous board.

Shareholders’ votes are being counted this weekend, and directors may have an idea of the result tomorrow.

Gounon said he wanted a turnout of at least 30% to demonstrate to creditors the shareholders’ determination to save the company. At last year’s tumultuous annual meeting 34% of shareholders voted — a more normal figure is 18%.

He said he was confident he would win, but did not rule out serving alongside Miguet.

If successful, Gounon will put a first draft of his restructuring plan to creditors on July 15. He has so far taken a hard line, saying creditors should write off about £4 billion of debt without penalty to shareholders.

“In each of the previous financial restructurings, the shareholders have taken the pain and they are not ready to take any more,” he said. City sources said last night that the speedy negotiations envisaged by Gounon, and his plans for a unilateral debt write-off, were unrealistic.

Eurotunnel has a complicated debt structure, with eight classes of debt having emerged from previous financial revamps. John Hatton, corporate analyst at the credit-rating agency Fitch Ratings, said Gounon’s plans “defied gravity”.

MBIA, the American bond- insurance group, has emerged as a key player in the talks because it controls some 50% of the voting rights of about £4 billion of the group’s “junior” debt. Eurotunnel shares closed last week at £16.75.

The Eurotunnel saga will be the subject of a special BBC2 Money Programme documentary on Tuesday. Gounon says in the report that the company will “inevitably” go bust if shareholders and creditors oppose the restructuring plans.

“˜The next moves by shareholders and creditors are Eurotunnel’s last rolls of the dice, and the management must throw double-six twice,” said BBC business editor Jeff Randall.

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