Work and Pensions Secretary Iain Duncan Smith's impassioned advocacy for reforming Britain's welfare system took a fresh blow as an official report heavily criticised his flagship policy, Universal Credit.

The findings of the National Audit Office (NAO) report, called Universal Credit: Early Progress, said its attempts to implement the major scheme were poorly planned, managed and resourced.

It found that the Universal Credit programme has experienced a volatile management culture as it had "five different senior responsible owners since mid-2012".

It also became increasingly clear that the Department for Work and Pensions (DWP) was failing to address recommendations from assurance reviews as it failed to fully implement two thirds of the proposals suggested by an internal audit completed by the Major Projects Authority in 2012.

The report criticised the limited pilot scheme that was started in April 2013 as "narrower than originally planned".

As a result the government has delayed the rollout of Universal Credit which was meant to happen in October 2013 and instead will add a further six pilot schemes to the one which already exists.

Problems of IT systems in the pathfinder schemes have led to a broader criticism that the DWP does not yet have a clear idea of what type of computer system will be provided for universal credit.

Similarly, the DWP's original plans to roll out the scheme so quickly were seen as over ambitious in that they failed to grasp the challenge of creating efficient IT systems to manage complex policies.

Furthermore, there is inadequate control over supplier spending, shortcomings in departmental oversight and a lack of transparency from those implementing the policy.

While the National Audit Office acknowledged "Universal Credit is a key programme" and could go onto "achieve considerable benefits for society", it made a number of recommendations.

These are to produce a more realistic plan with clear targets for Universal Credit, unify management structures, control spending and reassess its welfare programmes.

'Dysfunctional Money Pit'

Labour's shadow secretary Liam Bryne attacked Duncan Smith in the House of Commons.

"You must apologise to the House and you must now convene cross-party talks to get this project back on track. The quiet man must not become the cover-up man," he said.

Responding to today's report, the Trade Union Congress (TUC) also offered stinging criticism.

"This report is a damning indictment of what happens when one minister's ill- thought out hobby horse replaces proper policy development," TUC General Secretary, Frances O'Grady.

"The National Audit Office has exposed what a mess the government is making of implementing Universal Credit, which now appears to be a dysfunctional money pit."

In reply to such accusations, Duncan Smith fought back and blamed the flaws of Universal Credit scheme on the civil service.

With welfare reform a controversial subject for both politicians and voters and the 2015 election fast approaching, arguments over welfare are likely to get increasingly bitter as time goes on.