George Osborne's £3.2bn tax raid in doubt after finding fewer secret Swizz bank accounts than he hoped Chancellor hoped tax and levies would raise billions to pay down deficit But Swiss authorities say fewer Brits have accounts that first thought Office for National Statistics says it will only count the cash when it arrives Borrowing rises by £500million in June compared to same time last year George Osborne's plan to raise billions from a tax raid on secret Swiss bank accounts has been cast into doubt by the data watchdog. The nation's finances had been boosted by the prediction that the Chancellor's assault on tax dodgers would net an extra £3.2billion. But today the Office for National Statistics said there was now "significant doubt" about how much the plan would secure, and slashed the amount brought in so far to just £342million. Missing millions: There are now serious doubts about whether a tax raid on Swiss bank accounts held by Brits will raise as much as George Osborne hoped The government has staked both economic and political capital on clamping down on tax avoidance. In 2011 Mr Osborne signed a deal with the Swiss government to introduce a permanent tax for UK citizens with Swiss accounts. There was also a one-off payment imposed on May 31 this year to "clear past unpaid tax liabilities." Mr Osborne received a major boost last month when the ONS said the levy had secured a £3.2billion windfall for the Treasury, narrowing government borrowing from £15.6billion in May 2012 to £12.7billion this year. However it now says there are major questions about whether the money will ever materialise. The Swiss Bankers Association revealed earlier this month that there were fewer untaxed British assets in accounts in Switzerland than previously thought. Now the ONS has said the uncertainty means it will only count the funds raised towards cutting the deficit once it materialises. It means that the £3.2billion figure pencilled in for May 2013 has now been slashed to only £342million. "The recent announcement by the Swiss Bankers Association has cast significant doubt regarding the amount that will finally be received," the ONS said. Blow: Chancellor George Osborne had hoped to secure £3.2billion from the tax levies This suggests that a more cautious approach is now warranted and the payments will be included as and when payments are received. But the Treasury said: 'We have always been clear that the one-off payments are just one part of the tax we expected to recover under the Swiss agreement. Some people will instead choose to disclose their account to HMRC and pay the tax due, rather than authorise the banks to make a deduction. We expect to raise further sums through these direct disclosures, and through those made through other channels such as the Liechtenstein Disclosure Facility. The warning came as figures showed the government was forced to borrow an extra £500million last month in a blow to Mr Osborne's economic plans. Latest figures showed that public sector net borrowing - excluding distortions such as bank bailouts and quantitative easing - increased in June to £12.4 billion from £11.9 billion in 2012. Economists warned the jump in borrowing showed the nation's finances are still a "long way from health" despite signs of a recovery gathering pace. A Treasury spokesman said: "The Government is taking tough decisions to deal with the deficit: today's data shows that borrowing fell last year. And while we can and will take nothing for granted, the economy is moving from rescue to recovery: the economy is growing; the deficit and unemployment are falling. The independent Office for Budget Responsibility (OBR), set up to monitor the state's finances, expects the deficit to come in at around £120 billion this financial year - which would mark an increase on 2012/13. Higher local government borrowing in June offset a 15.2 per cent increase in tax receipts from businesses and households to drive the underlying monthly deficit higher. But the ONS said figures are likely to be subject to revisions as more data is received from councils. The ONS revised the underlying deficit for the year to the end of March 2013 lower by £2.3 billion to £116.5 billion due to higher tax receipts. That meant the 2012/13 deficit was £2.1 billion lower than in 2011/12, reversing last month's £300 million upward revision to the annual result. James Knightley, economist at ING Bank, said while borrowing was "not quite as good as hoped for," the numbers suggest the Government's full-year forecast remains on track. He added: "With economic activity starting to show some positive signs and with employment continuing to grow we would not be surprised to see the full year borrowing figure creeping below this forecast." But Martin Beck, UK economist at consultancy Capital Economics, said the UK's public finances remain a "long way from health." "While other indicators are pointing to signs of life in the UK economy, the public finances have yet to see much of a boost from the nascent upturn," he said. The OBR also warned over the Government's overstretched finances earlier this week, saying the UK's ageing population and strained healthcare system means an extra £19 billion of spending cuts or tax hikes are needed to combat "unsustainable" pressure on its coffers.