The government must pay careful attention to critical areas within the public services if extra funding is to bring improvements, according to a report published on Wednesday.

A total of £61 billion has been allocated towards investment in the public services for over the next three years.

However, the National Audit Office identified five generic risks faced by Whitehall in its use of resources, following the analysis of preparations made by the Department for Education and Skills, the Department of Health and the Department for Transport.

Complex delivery chains were a particular problem, according to the report, where several key organisations are involved in implementing policies.

In addition, attention should be paid to the capacity of organisations - particularly in the area of staff training.

The targeting of resources must be monitored to ensure that funds reach those areas of the public services that require them most, while departments must also assess the risks facing delivery organisations, said the NAO.

Ministers must also find a balance between ensuring that improvements in services are delivered while not imposing too much bureaucracy.

"This unprecedented increase in public spending equates to £1,000 for every person in the UK," said NAO chief Sir John Bourn.

"I continue to examine the value for money of individual projects and schemes but this report gives the opportunity to set out the fundamental issues that all departments need to address in the coming months and years in order to deliver a truly improved public service."