Image copyright Creative Commons Image caption Among the company's contracts is for cleaning at Network Rail stations

One of the UK's largest providers of public services is seeking a rescue deal as it struggles with £500m of debt, according to the Financial Times.

Interserve, which works in prisons, schools, hospitals and on the roads, said it might look for new investment or sell off part of the business.

Workers at the Foreign Office and the NHS are among Interserve's tens of thousands of UK employees.

The government said it supported the company's long-term recovery plan.

The Financial Times reported that the company was looking for a deal to refinance its debt which would mean lenders taking a significant loss while public shareholders would be "virtually wiped out".

Its share price dropped to a 30-year low last month.

Despite lucrative contracts in the Middle East and its wide range of work in the UK, the company has continued to lose money since March, when it agreed an earlier rescue deal.

Its troubles have been blamed on cancellations and delays in its construction contracts as well as struggling waste-to-energy projects in Derby and Glasgow.

Interserve claims its prospects are improving, and says it will increase profits this year.

What does Interserve do?

From its origins in dredging and construction, the company has diversified into wide range of services, such as health care and catering, for clients in government and industry.

At King George Hospital in east London, for instance, Interserve has a £35 million contract for for cleaning, security, meals, waste management and maintenance.

Its infrastructure projects include improving the M5 Junction 6 near Bristol, refurbishing the Rotherham Interchange bus station in Yorkshire, and upgrading sewers and water pipes for Northumbrian Water.

But Interserve is also the largest provider of probation services in England and Wales, supervising about 40,000 "medium-low risk offenders" for the Ministry of Justice.

In a statement, Interserve said: "The fundamentals of the business are strong and the board is focused on ensuring Interserve has the right financial structure to support its future success."

The company said its options included bringing "new capital into the business and progressing the disposal of non-core businesses ".

Interserve's difficulties follow the collapse of Carillion in January 2018, which put thousands of jobs at risk and cost taxpayers £148m.

Following that, the government launched a pilot of "living wills" for contractors, so that critical services can be taken over in the event of a crisis. Interserve is one of five suppliers taking part.

A Cabinet Office spokesperson said: "We monitor the financial health of all of our strategic suppliers, including Interserve, and have regular discussions with the company's management. The company successfully raised new debt facilities earlier this year, and we fully support them in their long term recovery plan."