Tory leader David Cameron will set out plans for a radical overhaul of the benefits system designed to end the culture of welfare dependency and get the growing army of unemployed back to work.

On the eve of the party's annual conference in Manchester, he said an incoming Conservative government would scrap Labour's flagship New Deal welfare-to-work programme and replace it with a new, simplified "Get Britain Working" plan.

However Mr Cameron faces a growing row within his own ranks over Europe in the wake of yesterday's Yes vote in the Irish referendum on the controversial Lisbon Treaty.

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The result removes a major obstacle to the treaty's final ratification and Tory Euro-sceptics are now demanding an assurance that he will go ahead with his promised referendum on the treaty, even if it has been fully implemented by the rest of Europe by the time the Tories take power.

So far he has resisted their calls, knowing that they could place a new Conservative government on a collision course with the rest of the EU if they try to reopen the treaty.

Last night he was continuing to stick to the line that there was no need to decide now what they would do as Poland and the Czech Republic had still to ratify.

"There are still two countries in Europe that are yet to ratify. I don't want to do anything or say anything that actually prejudices the outcome in those countries," he said.

But with Poland expected to follow Ireland's lead and rapidly ratify, the Euro-sceptic Bruges Group said Mr Cameron must make his position clear.

"If David Cameron is serious about becoming Prime Minister then he must show leadership and announce that a retrospective referendum will be held in Britain. This will rule the Lisbon Treaty null and void in the UK and withdraw us from its provisions," it said.

Mr Cameron will hope that he can shift the focus on to his domestic agenda and his programme for welfare reform.

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Writing in The Sunday Telegraph, he said a Conservative government would dismantle Labour's "big government labyrinth" and simplify the system to provide more personalised support for people seeking work.

"The urgency of this crisis and the scale of the suffering is why we're putting this problem - and our solution - front and centre at our conference," he said.

"We won't get Britain back to work through Labour's big government solutions. It is big government that has stifled innovation and crushed enterprise - the very engines of growth and job creation."

In a separate article for the News of the World he described the Tories proposals as "the biggest shake-up in welfare for 60 years".

"It is vital that we get to grips with this problem. It's not just that it comes with a price tag of tens of billions a year. It's that mass unemployment can lead to massive social problems - like family breakdown and crime - and that affects us all," he said.

"A crisis of this scale, that runs so deep, cannot be solved with one policy or programme alone. It means ripping up the old way of doing things and bringing radical change across the whole of our economy."

Tory sources said that it would be a comprehensive package to tackle long-term unemployment and reduce the cost to the taxpayer of the 2.6 million people currently on incapacity benefit.

It is reported to include American-style measures to use private firms - who are paid by results - prepare people for employment and place them in jobs.

It was also said to involve the introduction of rigorous medical checks to to establish whether people claiming incapacity benefit are capable of working.

Shadow work and pensions secretary Theresa May said: "Under Labour we've seen a comprehensive failure to tackle the growing dependency culture and challenge of the long-term unemployed.

"For too long Labour ducked welfare reform and too many people have suffered as a result. We are determined to change this with a radical and bold plan to deal with Labour's jobs crisis and get Britain working."

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