Britain\'s government borrowed less than expected in May owing to one-off factors, official data showed on Friday, boosting finance minister George Osborne ahead of his latest spending review due next week. Public sector net borrowing, a measure of the public deficit, stood at £8.8 billion ($13.6 billion, 10.3 billion euros) in May, the Office for National Statistics (ONS) said in a statement. Market expectations had been for a smaller drop last month to £12 billion, according to analysts polled by Dow Jones Newswires. The coalition\'s net borrowing had stood at £15.6 billion in May 2012. May\'s 2013 data was flattered by an estimated £3.2-billion payment from Swiss banks under the new Britain-Switzerland tax treaty, and by a £3.9-billion transfer of profits from the Bank of England\'s bond-buying programme, the ONS said. Stripping out both exceptional factors, state borrowing stood at £15.9 billion in May -- which was slightly higher than the figure for the same month of 2012. In January, the government struck a deal with Swiss authorities to recoup tax from British residents\' bank accounts in the country. The ONS added that the £3.2 billion figure was an estimate, while the actual amount would be confirmed upon receipt in July and August. The data was published ahead of Osborne\'s spending review due next Wednesday. Chancellor of the Exchequer Osborne will outline how he will tackle high levels of state borrowing when he reveals the outcome of his 2015/2016 spending review. \"May\'s UK public finance figures provide further evidence that government borrowing is back on an improving trend, although mainly due to temporary factors,\" said economist Vicky Redwood at research consultancy Capital Economics. \"With borrowing still at very high levels, next week\'s spending review is a reminder of how much austerity still lies ahead. Indeed, the review will detail how only a fraction of the pain that still lies ahead will be achieved.\"