Whitehall spent at least £275 million in one year on staff training, although the true cost was likely to be "significantly" higher, a spending watchdog has warned.
A probe by the National Audit Office (NAO) showed that while the Government estimated it spent £547 on each civil servant during 2009/10, it did not actually know exactly how much it had paid out.
Despite the high costs involved the impact of the skills sessions were rarely evaluated and more than half of staff involved did not believe they were any better at their job as a result of the course they had been sent on, it added.
The NAO also criticised the failure of Government to use its mighty buying power to secure the best deal when outsourcing training.
More than 250 different leadership courses were being used across departments, with charges varying four-fold between the cheapest and the most expensive daily rates.
There was also poor monitoring of whether staff actually turned up to the costly courses.
Margaret Hodge, chairman of the Public Accounts committee, said: "We have heard many times about how the lack of skills in areas such as finance, IT, procurement and project management has contributed to waste, inefficiency and multiple project failures in government.
"It has also led to unnecessary spending on expensive consultancy advice.
"Each year departments spend at least £547 per civil servant on developing skills and yet they don't know what they are getting for their money, or if it is having any positive effect at all.
"In a time when headcount reductions are taking place and major reform programmes are under way, it is vital that government gets a grip on the skills it needs to deliver its objectives, and gets value for money for investment in developing its staff."
The NAO warned of the "wasted investment" in skills development, pointing to the Civil Service People Survey in 2010 that showed only 48% of workers said the learning and development they had received in the last 12 months had helped them be better at their job.
But, more significant was the impact lack of proper training had on the "effectiveness" of departments, it added.
Responsibility for training has been unclear, leading to "incomplete and unreliable" information on how much courses have cost.
Work has already started on tackling the problems with a new cross-government development department, Civil Service Learning, set up in April, but it was too early to say how that would work out.
Amyas Morse, head of the National Audit Office, said today: "Tight public funding means that departments must find ambitious new ways of working to maintain and drive up levels of performance.
"Key elements of success will be knowing what skills are needed and which staff have them, and then deploying those staff to where they are most needed.
"These key elements are not presently in place in many departments and need to be driven urgently to be in step with major change programmes."