Civil servants' union PCS demanded yesterday that the Department of Work and Pensions (DWP) renationalise its computer development work after tech firms squandered £140 million on a useless IT system.

A Commons public accounts committee report blasted the Tories' flagship universal credit scheme, which was to utilise the IT system, as a "shocking" failure.

In a strongly worded report, MPs voiced doubts about whether the £425m shake-up of the benefits system can still be finished by 2017.

They said a trial run had been "inadequate."

The committee found personal assistants had been signing off unauthorised transactions totalling £20m.

Chairwoman Margaret Hodge MP said: "It is likely that much of this, including at least £140m worth of IT assets, will now have to be written off."

PCS said it had warned the government from the off that "such a massive change to the social security system was practically impossible to implement."

And the project was "the latest in a long line of IT failures by the private-sector IT companies working on DWP contracts.

"Yet again these companies have promised a state-of-the-art IT system and completely failed to deliver."

The DWP used to develop IT systems in-house until it was privatised in the early 1990s.

Since then there have been a number of high-profile failures.

A system for the Child Support Agency brought online in 2003 lost files, forcing admin staff to fill in cases by hand.

A bug-ridden benefit claims project in 2005 had similar problems.

The failures aren't just confined to the DWP, with government-funded computer catastrophes occurring all over the shop because of IT firms failing to deliver on promises.

These include a disastrous £12 billion NHS IT scheme and a scrapped £500m computer system for the fire service.

PCS general secretary Mark Serwotka said: "This is an absolutely scandalous waste of public money.

"DWP must stop awarding contracts to these IT failures and bring this IT work back in-house."