Employing disabled people would be a priority for recruitment in Whitehall and the public sector under a Tory government, David Cameron has said.
Mr Cameron says employers' attitudes have to change
He said 50% of disabled people of working age are not in work and have been "simply written off".
The Tory leader said it was "morally wrong" that 5m people who could work were not working and yet migrants were filling gaps in the labour market.
But minister Jim Murphy said Mr Cameron had inflated the unemployment figures.
Mr Cameron, whose four-year-old son Ivan has cerebral palsy, spoke out during a wide-ranging speech on disability in Edinburgh.
He called for more to be done to give disabled people incentives to work through reforms of the incapacity benefits system.
He also revealed that his party has called in the charity, Scope, to give advice on candidate selection and to help devise employment policy welcoming applications from people with disabilities.
He said that if the Tories won the next general election "we will make the employment of disabled people a priority for recruitment policy throughout Whitehall and the public sector.
"If we're going to change attitudes in our country, government needs to set an example. That is what social responsibility means.
"I want to see employers welcome disabled people."
Mr Cameron said it was "outrageous" for Chancellor Gordon Brown to claim that the UK nearly has full employment.
"Real unemployment in Britain is around five million - five million people left on the scrap-heap while British firms deal with the resulting labour shortage by employing migrant workers," he said.
"That is morally wrong and economically stupid and it has to stop.
"We have a social responsibility to help disabled people into the workforce.
He added: "For the sake of the people who are locked into welfare; for the sake of taxpayers and for the sake of our economy, we have to bring them back into the mainstream, into work."
However, Mr Cameron argued that filling gaps in the labour market with migrant workers was "a good thing, not a bad thing".
"We should not try to unlock the potential of our own citizens by locking out the citizens of other countries," he said.
"When willing, able and energetic people come to this country to work, they don't crowd out other people from the labour market."
But employment minister Mr Murphy said the claim that five million more people could be working implied that every lone parent claiming income support and every incapacity benefit claimant - even those with serious disabilities - should be looking for a job.
"David Cameron has today shown serious misjudgement in seeking headlines by wildly inflating the unemployment figures," he said.
"He makes a major gaffe by treating as ready for work the seriously ill and lone parents whose children are only a few weeks old.
"Cameron's inaccurate and irresponsible claims will frighten people whose health conditions mean they need increased support to get back to work, and he will worry mothers by seeming to suggest they should be looking for work as soon as their child is born.
"Cameron's gaffe today shows the Tories have no credibility on changing the welfare state so it better supports people to find a job."
In his speech, Mr Cameron also said the benefits system often penalises people who suffer from fluctuating conditions, like Multiple Sclerosis or Bipolar Disorder.
If they suffer a relapse of the condition and have to give up work, they often have to start the whole assessment process again, he said.