LONDON (AFP) - The number of unemployed in Britain has hit 2.5 million after rising for the first time in six months, official data showed Wednesday, as economists predicted further gloom amid deep spending cuts. The jobless total rose by 35,000 in the three months to October to reach the landmark, the Office for National Statistics (ONS) said in a statement. The ONS added that the unemployment rate rose to 7.9 percent in the three months to October from 7.7 percent in the three months to September. Prime Minister David Cameron expressed concern over the latest jump in unemployment -- but argued that the data painted a mixed picture. "Of course anyone should be concerned and I am concerned by a rise in unemployment," Cameron told lawmakers at his weekly question-and-answer session in parliament on Wednesday. "Anyone who loses a job (it) is a tragedy for that person and we must do everything we can to help people into a job." He added: "Whilst part of the figures are disappointing ... they are mixed because we see the claimant count has come down in the unemployment figures." The claimant count -- the government's preferred measure of people who claim unemployment benefits -- fell 1,200 in November to 1.46m. Cameron's Conservative-Liberal Democrat coalition government is slashing expenditure and increasing taxation as it seeks to tame an enormous public deficit. A government watchdog, the Office for Budget Responsibility (OBR), has forecast that about 330,000 jobs will be shed in Britain's public sector over the next four years as a result of the planned austerity measures. "The UK labour market appears to be flagging even before the full force of the public sector job cuts hits," said Vicky Redwood at the Capital Economics consultancy in London. "Overall, we still find it hard to share the OBR's optimism that the private sector will more than offset the looming public sector job losses and expect unemployment to rise quite sharply over the next couple of years."