The working tax credit, promised Mr Blair, would ensure that every single disabled person employed on a full-time basis would earn at least £150 a week.

Legislation for the scheme to get disabled people into work is to be launched by Chancellor Gordon Brown next week.

It will also include measures to create Britain's "first ever" Disability Rights Commission, which would work along the lines of the Equal Opportunities Commission.

'Work pays'

The prime minister's announcement came in a question and answer session in Hounslow, west London, before an audience of disability rights groups representatives on Friday.

He said: "The government will launch the first-ever disabled person's tax credit.

"This credit, which is going to be similar to the Working Families' Tax Credit, will ensure that work pays for disabled people.

"One of the things that is happening in this country is that there is a hidden revolution happening in the tax and benefit system.

Tony Blair: Those too ill will not be forced to work

"It is part of the strategy to try and ensure that work does actually pay for disabled people."

He later said: "The purpose of the commission will be to provide information and advanced codes of practice, and it will be able to conduct formal investigations and to build on the best practice of the Equal Opportunities Commission and the Commission for Racial Equality."

The prime minister said a similar system in the US had been met with scepticism, but was now acknowledged as a great success.

But he faced some searching questions from members of the audience.

They wanted to know whether the benefits reforms would ensure that they were not penalised by seeking work.

'Dialogue and consensus'

He reiterated previous assurances that people who were too ill to work - either through physical or mental disabilities - would not be forced to do so.

Mr Blair said the process of reform would involve "dialogue" and "consensus".

He said: "The danger for politicians, but also for everyone, is that when talking about disability issues, that we approach this in a way of saying 'What can we give to disabled people?'.

"But actually this should not be like that. It should be about 'how do we fulfil the potential and give opportunities to people to make the most of what they have?'."