David Laws launched a stinging attack on the Tories, claiming their policies were designed to widen inequality and undermine public services.

During a debate on the economy, the Somerset MP, who chairs the party's manifesto working group, said: "In the next parliament, we must plan to complete our historic task of clearing up the economic mess we inherited from Labour in 2010. Unlike Ed Miliband, we will not forget out responsibilities to restore sound public finances in this country.

"We will commit to finishing the job of deficit reduction in full and on time and then we will set out a course to reduce public sector debt to safe levels. But unlike the Tories, our pre-manifesto commits us to finishing the job fairly, with the rich making a proper contribution to deficit reduction."

Mr Laws said there was not "some trivial political dividing line" between the main parties but "fundamental differences in policy and values".

He claimed the most eccentric speeches of the conference season were delivered by David Cameron and George Osborne.

"Their extraordinary proposition was this: they would cut the incomes of the poorest if they are re-elected to help fund tax cuts for the richest in society. And not a penny would be raised from taxation to meet the need to cut the deficit further.

"Conference, we as a party will have no part in such a strategy now or after the next election," declared the English Schools Minister.

He highlighted several policies implemented by the party, from the £10,000 tax allowance and the Green Investment Bank to free school meals for infant school children and same sex marriage.

"We have, then, achieved far, far more than any other group of Liberals or Liberal Democrats in the last 100 years," the Minister declared.