VINCE Cable has branded George Osborne a liar for suggesting the Tories could balance the nation's books without raising taxes.

In more pre-election rhetoric aimed at putting clear yellow water between the Liberal Democrats and the Conservatives, the Business Secretary branded his Coalition partners "Ukip without the beer" and said they were "ideologically" committed to destroying public services and the welfare state.

Signalling a more aggressive approach in a bid to revive his party's poll ratings, wallowing at just seven per cent, Nick Clegg, earlier, used a round of broadcast interviews to accuse the Chancellor of planning to "balance the books on the backs of the poor", while Tim Farron, the party president, accused the Conservatives of being "borderline immoral" in their approach.

In a series of barbed assaults on political opponents, Mr Cable told activists that Labour was offering "French Socialism without the sex".

But he reserved his most hostile passages in his keynote speech for the LibDems' partners in government, whom he lambasted as "arrogant" and a home for "dodgy billionaires".

Referring to Mr Osborne's proposal last month for a further two-year freeze on working-age benefits, Mr Cable said: "The need for budget discipline mustn't become an obsession with ever deeper cuts in public spending.

"Key public services have already been cut to the bone from legal aid and local government to policing and defence.

"The Tories are ideologically obsessed by cuts because they see it as a way of destroying public service and the welfare state, which they detest.

"The Tories' proposal to take another £25 billion or more out of welfare and unprotected Government departments will do great harm to valuable services: to imagine otherwise is fantasy. I will categorically not go along with this," declared the London MP.

He went on: "The truth is more taxes will be needed; to contribute to deficit reduction and also to address unacceptable inequalities. Any politician who tells you that the next Government can balance the budget and avoid tax increases is lying to you."

Last week at the Conservative conference, the Chancellor suggested just that with the Prime Minister pledging tax cuts for 30 million people, coming in at, an as yet uncosted, £7 billion.

In contrast, the LibDems insist the deficit should be eliminated through a mix of 80 per cent spending cuts and 20 per cent tax rises; they plan to up taxes on the wealthy, including through a new tax on homes worth more than £2m, the so-called mansion tax.

Taking a significantly different tone to the Chancellor on managing the public finances, Mr Cable said borrowing should be allowed to rise for capital investment in housing and transport, insisting when interest rates were low, it was a "no brainer" to borrow to invest.

The Secretary of State also drew a sharp dividing line with the Tories over immigration, describing their immigration cap as "absurd". He said: "Our responsibility as Liberal Democrats is to tell the uncomfortable truth: that the vast majority of migrants coming to the UK from inside or outside the EU have brought tangible benefits to the economy, importing valuable skills and strengthening our civic culture.

"Of course, immigration does have to be controlled at the point of entry and exit and we must deal with abuse and crack down on 'benefit tourism', but not at the expense of the EU Single Market and its free movement of workers."

In a later question and answer session, the Deputy Prime Minister, defending Britain's membership of the European Convention on Human Rights, also attacked the Tories, saying: "It perplexes me utterly when you hear people like (Justice Secretary) Chris Grayling in a desperate, pathetic attempt to curry favour with Ukip or at least scamper after Ukip, now saying they will chuck those great British principles of liberty overboard. We should be proud of the fact as a country we were the authors in so many respects of those liberal principles enshrined in that document which countries like Russia and Belarus should abide by.".