It found that 70% of employers have never heard of a �50m financial support scheme for equipment, ramps and other aids, known as Access to Work (ATW).

The RNIB says there is huge potential for disabled people to find jobs, as job centres have 600,000 vacancies.

The Department of Work and Pensions has defended its efforts.

In its report, the RNIB calls on the government to say how much it spends on promoting the funds available.

A DWP spokeswoman pointed out that a "large amount" of money was spent on the scheme and that figure was increasing each year but she was unable to comment on the publicity spend.

"We are committed to helping blind and disabled people back into work," she told BBC News Online. "There's also the Pathways to Work scheme to help people on incapacity benefits back into work, many of them blind and disabled."

'Obvious benefits'

The RNIB estimates the amount spent on publicity "could be as little as �37,500 a year".

"We've asked the government repeatedly, and we've tabled questions in the House (of Commons)...and the government won't say how much they're spending on (promoting) ATW," said RNIB spokesman Bill Alker.

The RNIB considers ATW "far and away the most successful" out of eight government-backed schemes to support disabled people at work which have a total publicity budget of �300,000.

The government's failure to publicise ATW funds is "a missed opportunity", said Mr Alker.

"The financial benefits are absolutely obvious because the returns to the Treasury are far greater from a person being in work than a person being on benefits," he told BBC News Online.

Over the last three years, 36,606 disabled people have benefited from ATW, an average payout of �1,202.

Economic benefits

Even low-paid workers quickly repay the cost of supporting them into work, the RNIB calculates.

It says someone earning as little as �12,000 a year would bring benefits to the Treasury of �2,145, more than the average ATW payout, whereas on benefits they would cost the taxpayer a minimum of �4,261 in Incapacity Benefit.

"The government should be banging a drum for ATW," said Steve Winyard, the RNIB's head of public policy, and chair of the Disability Employment Coalition, a 13-charity umbrella group.

There are currently one million disabled job seekers.

Only people who have been offered a job are eligible to apply for ATW, but "it's extremely advantageous to a person to know about ATW. It can make a crucial difference to a person getting a job or not," said Mr Alker.

He gives the example of Liz Yates, who had worked for Bespak in King's Lynn for nine years when she found she was losing her sight, and risked losing her job.

Fortunately, her employer looked for ways to keep her. An ATW grant enabled the firm to obtain technologies that enlarge text on screen and help her to see across the room.

More help needed

Delays in ATW funding can also lead to candidates being turned down for jobs.

Kelly Muggeridge, 35, found a job as a medical secretary in Crawley, Sussex, but says the hospital "withdrew their offer because ATW quoted 12 weeks to provide computer equipment that I needed to do the job".

"I was absolutely devastated," said Ms Muggeridge, who is still unemployed.

The RNIB wants a statutory appeals process created to deal with such failures, and with outright refusals to provide ATW, as the grant remains discretionary.

The DWP supports eight schemes altogether, spending �300,000 in total on publicising them.

The DWP says the full �50m is spent annually, suggesting there is little problem with take-up, the RNIB acknowledged.

The charity believes ATW should be expanded, arguing that demand for the funding is set to increase in October when small firms with less than 50 workers have to comply with anti-discrimination laws that oblige them to make "reasonable adjustment" for disabled workers, exactly the kind of workplace alterations that ATW is designed to fund.