British finance minister George Osborne ruled out Sunday the Liberal Democrats' idea of a "mansion tax" on properties worth more than £2 million. Speaking before the Conservative Party's conference begins in Birmingham, Chancellor of the Exchequer Osborne warned that if introduced, it would quickly spread to more modest homes. "We are not going to have a mansion tax or a new tax that is a percentage value of people's properties," he told The Mail on Sunday newspaper. "Before the election they will call it a mansion tax, but people will wake up the day after the election and discover suddenly their more modest home has been labelled a mansion. "We don't think people who have worked hard, saved up to buy a home, should be clobbered with a mansion tax." The Lib Dems, the Conservatives' junior partners in the coalition government, have warned that they will not stand for further belt-tightening without fresh measures targeting the richest. Osborne said the government would be extending the council tax freeze for a third straight year while rises in regulated rail fares would be capped at four percent. The Tatton MP said he would not "flinch" from his programme to rein in overspending. "Western countries face a simple choice: Are they going to sink or swim?", the 41-year-old said. "There will be lots of countries, neighbours of ours, who are going to duck difficult choices. In 20 or 30 years' time they will be much poorer." The Treasury chief declined to say when he thought the recession would end, though he said: "The economy is healing. But it's a longer and harder road that we have to travel down. There will have to be further cuts."