The company employs 75,000 people worldwide, including 45,000 in the UK, and has been in financial difficulty for some time, in part as a result of pressure on margin in the outsourcing business and expansion into sectors such as waste energy. It is responsible for a number of key government outpouring arrangements, including cleaning the London Underground.

Last month it outlined a plan to reduce its net debt to £275m by issuing £480m of new Interserve equity. However, this new equity will be placed with the company’s existing lenders, who will then hold 97.5%, with ordinary shareholders left with just 2.5% of the equity in the company.

The proposal has attracted strong opposition, notably from US hedge fund Coltrane Asset Management which has a 27.7% stake in the company. Coltrane has said it will block the board’s plan and has put forward an alternative option.

Coltrane has not made a public formal approach with its proposals, and, Interserve stated: ‘The ability to obtain lender support for a materially different deal requiring lenders to take significantly larger write offs, or provide ongoing support, in the short time frame available is therefore unknown.’

In a statement to shareholders ahead of Friday’s vote, Interserve said its deleveraging solution is ‘the only plan today that is capable of being implemented, preserving some value for shareholders.’

The statement went on: ‘It is the only plan today that is capable of implementation in order to provide balance sheet strength and cash liquidity to allow the group to meet its financial obligations and provide stability for the future.

‘The company is in a critical financial situation. The deleveraging plan is the result of months of complex intensive negotiation with lenders, bonding providers and the pension trustee.

‘Our plan preserves some value for shareholders. This will not be the case if the proposals are voted down. It is the only plan with the support of all of our lenders and the pension trustee.’

Over the weekend, Interserve chairman Glyn Barker said in media interviews that if the plan was not agreed, then the company would ‘run out of money’ and he expected the company’s lenders to call in a £66m loan which it would not be able to repay.

The company statement said: ‘If shareholders do not support our plan we have taken steps to prepare for an alternative transaction to protect the business and preserve value for our creditors, customers and our suppliers.

‘However, this is an outcome we would much prefer to avoid as it would likely result in no return for shareholders and it is more costly and disruptive to Interserve.’

Interserve is understood to have lined up EY to handle a possible administration if it fails to get sufficient support for its deleveraging plan.

Report by Pat Sweet