The Highways Agency "lacks basic facts about what it gets in return for taxpayers' money", a report from MPs said today.

There was a wide variation in the costs of jobs between different agency areas, the report from the House of Commons public accounts committee said.

And MPs said it was "disturbing" that the agency, responsible for England's motorways and major A roads, did not fully understand how much the costs of road resurfacing had increased.

There was concern that despite successive initiatives, there have been only limited improvements in safety levels at roadworks - for either users or workers.

MPs also expressed concern that the latest year for which road worker injury statistics were available was 2006.

Committee chairman Edward Leigh MP said road maintenance work had improved journey times on major routes, but value for money was still in "serious doubt".

"The basic point is that the agency does not know enough about what it is getting for the taxpayers' money it spends on maintenance across its whole network. Without a better understanding of the costs of network-wide activities, such as resurfacing, it cannot hope to drive those costs down," Leigh said.

He added: "The agency must maintain and improve the commercial skills and technical knowledge of its staff. It must be better informed and more robust in its management of contractors, not just at the procurement stage but also over the whole life of the contract."

Highways Agency chief executive Graham Dalton defended the performance of the body, saying it was strengthening its commercial management skills.

"To further improve value for money and delivery we are strengthening our commercial management teams and taking action to control costs," Dalton said.

He added: "The agency takes safety of road workers and road users very seriously and keeps detailed and up-to-date records of road worker casualties on our network."

Shadow transport secretary Theresa Villiers said the criticisms of the Highways Agency were "symptomatic of government failure".

"It is the government's job to ensure the taxpayer gets value for money in relation to road repairs and maintenance which can have an impact, not just on car wear and tear, but on road safety as well," Villiers said.

"This report is further proof that Labour are incapable of managing our vitally important road network efficiently or safeguarding taxpayers' money. We can't go on like this."