Railtrack finally collapsed yesterday under the burden of £3.3 billion in debt after the government refused to give the ailing rail infrastructure company any further cash.

Administrators were appointed after the government gave the green light to put the firm into liquidation.

Stephen Byers, the transport secretary, said: "Railtrack is finished."

Ministers want to replace the firm with a not-for-profit trust which will invest any revenues generated back into the rail network.

The government will, however, stump up the £3.3 billion to service Railtrack's borrowing and pay its creditors until the new trust is established.

Shareholders are being told not to expect any return on their investment.