Treasury Chief Secretary Danny Alexander has launched a major crackdown on tax-dodgers, insisting everyone must "play by the same rules" as the country faces further austerity.

Up to £3 billion could be raised by targeting Britons who stash their money in Liechtenstein, Mr Alexander said as he set out plans to tackle the use of tax havens.

Mr Alexander also stressed that the Liberal Democrats would continue to press for a mansion tax on high-value homes, which Business Secretary Vince Cable claimed was being blocked by Tory "backwoodsmen" opposed to the levy.

The Independent reported that additional council tax bands could be used as a method of targeting high-value homes.

Mr Alexander said: "The Liberal Democrats have a clear policy. We believe that there should be an extra levy on high-value homes worth over £2 million. It's what we argued for in opposition, it's what we stood for election on in our manifesto last time and it's what we will continue to argue for."

He added: "There is a broader point which is, as we move into the next phase of deficit reduction when we are going to have to make painful choices about public spending, about welfare cuts and so on, then we have to make sure that the wealthiest in society pay their fair share of that extra burden that the whole country is facing."

Endorsing Chancellor George Osborne's attack on tax-dodgers, Mr Alexander said the practice was "totally morally repugnant" as he claimed the clampdown will bring in billions for the Exchequer.

He said: "We will bring in billions of pounds more. One of the things that many people do to try and avoid the British tax system is to take their money away to offshore tax havens. In just one such haven, Liechtenstein, we think now we can raise £3 billion from people who try to hide their money from the British taxman in that country. It is totally morally repugnant for people to engage in tax evasion, to engage in aggressive tax avoidance."

Mr Alexander signalled that further welfare cuts would be necessary as well as extra taxes on the wealthy. He said: "We have taken a lot of steps as part of dealing with the deficit but, as that goes on for longer, we have to take more steps on public spending, we have to take more steps on welfare. We have to take a lot more steps on the wealthy too."

Meanwhile, at the party's conference in Brighton, Lib Dem leader and Deputy Prime Minister Nick Clegg has announced that town halls are to be given £100 million to spend on new nursery places to ensure poor families can take advantage of a Government guarantee of free childcare. From September next year, 130,000 of the most disadvantaged two-year-olds will qualify for 15 hours a week, with the number set to double in 2014 - at a cost of £760 million a year.