Eurotunnel is currently battling huge debts

The firm said Roger Bruge, who had been leading the group's financial overhaul, had left for "personal reasons".

The news followed a meeting between the group and the French government which failed to solicit any pledge of cash help for the debt-ridden firm.

Its debts are currently just over �6bn, and early this week the firm revealed falling sales had seen revenues slide 5% to 125m euros (�82m or $149m).

Mr Burge, who had held his post since February 2002, was one of the survivors of a recent boardroom coup led by disgruntled shareholders.

That led to the replacement of the group's chairman and chief executive.

In a separate statement the firm said it had held "constructive" talks with French finance minister Nicolas Sarkozy earlier this week.

Credit crunch

But it did not reveal whether any French aid would be forthcoming.

The statement added: "The minister confirmed that the French government is closely monitoring the situation at Eurotunnel, and that the French ministry for the economy, finance and industry would bring its technical expertise in financial matters."

Investors have called for state help from both the UK and France - something both governments have so far refused to do.

French Transport Minister Gilles de Robien has argued that an Anglo-French treaty forbids state subsidies.

Meanwhile , in 2006, Eurotunnel faces the end of the so-called "minimum usage charge" - an agreement which guarantees minimum revenues from rail operators.

This means its income is likely to fall unless it can boost its passenger and freight traffic.