More than half of those on sickness benefits across parts of Scotland are being told they are fit to work immediately.

Rates of those judged healthy enough to hold down a job are far higher in Clackmannanshire and Falkirk than the one-in- three UK average.

But campaigners and opposition politicians denounced the system as flawed and pointed out that almost four in 10 decisions are overturned on appeal.

The Coalition is reassessing more than a million people claiming incapacity benefit across the UK, as it attempts to cut £16 billion from the welfare bill.

Ministers insist the tests are necessary to save money and free hundreds of thousands of people "trapped" on benefits.

However, the tests have proved highly controversial amid accusations they are too blunt and easily misjudge individual circumstances.

Earlier this year, the Government was forced to announce a series of changes designed to cut the number of appeals upheld.

The figures, released yesterday, come just weeks after the Government announced the first tranche of UK-wide results which suggested that one in three people were being told they were fit to work.

In some parts of the country that figure is much higher. In Clackmannanshire 51% of those tested were told they were fit to work, the highest percentage in Scotland.

In Falkirk that figure was 48%, in Stirling 44% and in North Ayrshire 40%.

Across Scotland the average was slightly lower than it was across the rest of the UK, at 31%, with the lowest figure in Perth and Kinross at 19%.

Last night, Chris Grayling, the Conservative Employment Minister, said that the figures proved "how much of a waste of human life the current system has been". "Too many people have been left languishing on benefits for too long," he said.

The Government has begun a Work Programme designed to help thousands of people back into work.

But the programme has also attracted controversy for paying companies up to £14,000 per intervention and for ignoring smaller groups and charities when awarding contracts.

Critics said the system was flawed and that many ill people had been wrongly told they were healthy.

Dame Anne Begg, the Labour Aberdeen MP who chairs the Commons Work and Pension Select Committee and who has been a noted critic of the assessments, said: "The thing that worries me is that I think there are people who have health impediments to getting a job sitting in the 'able to work' group because of the way the assessments have been carried out."

She pointed out that there were a high proportion of people claiming sickness benefits.

She added: "There are people who qualified under the old criteria but not the new criteria, but that doesn't make them benefits cheats."

Citizens Advice Scotland have warned that more than 100,000 sick and disabled Scots could lose £390 million over the next three years after being told that they are fit for work.

The charity says the changes could have a "devastating impact" on some of the poorest families.

Around 1.5 million incapacity benefit claimants will be reassessed as part of the Coalition's plans over the next three years.

They are then told whether they are considered fit enough to return to work immediately, whether they will someday be able to return to work with support, or whether their illness is considered so disabling that it prevents them from working.

Ministers warn that before they started the tests, some of those on benefits had not been assessed for more than a decade.